Newton's laws

1. Introduction

2. Force

3. Basic types of forces



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Identifying the normal force

The following free-body diagram shows five forces acting on an object that is in contact with a horizontal surface.

Which one of the forces represents the normal force?

Answer:

The normal force is represented by:


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Identifying the normal force

The following free-body diagram shows five forces acting on an object that is in contact with a slope.

Which one of the forces represents the normal force?

Answer:

The normal force is represented by:



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Working out the normal force

William is investigating the motion of an object as it slides to the right along a rough horizontal surface.

The following force diagram shows all the forces exerted on the object except for the normal force.

Which one of the following force diagrams shows the correct size and direction of the normal force Fโ†’N?

A

B

C

D

Answer:

The normal force is correctly shown in diagram:


ID is: 3454 Seed is: 3413

Working out the normal force

Luyanda is investigating the motion of a crate as it slides down a rough wooden ramp.

The following free-body diagram shows all the forces exerted on the crate except for the normal force.

Which one of the following free-body diagrams shows the correct size and direction of the normal force Fโ†’N?

A

B

C

D

Answer:

The normal force is correctly shown in diagram:



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Definition: The normal force

Define the term normal force using the dropdown menus below.

Answer:

The normal force (Nโ†’ or Fโ†’N) is the force which a exerts on an object with which it is , and which points the .


ID is: 3325 Seed is: 5533

Definition: The normal force

Define the term normal force using the dropdown menus below.

Answer:

The normal force (Nโ†’ or Fโ†’N) is the force which a exerts on an object with which it is , and which points the .



ID is: 3677 Seed is: 5105

Factors affecting kinetic friction

An object is sliding along a rough horizontal surface.

As the object slides, it experiences the kinetic frictional force (fโ†’k). Various properties of the object and the surface will affect this force, but some will not.

  1. For each property below, decide whether it does or does not affect the magnitude of the kinetic frictional force experienced by the object.

    Answer:

    The magnitude of the kinetic frictional force is affected by:

    • the contact surface area between the object and the surface:
    • the distance travelled by the object:
    • the material the object is made from:
  2. The object is covered with a thin layer of smoother material. Will the magnitude of the kinetic frictional force increase, decrease, or remain the same?

    Select a reason for your answer from the table of reasons given below. Assume that all other properties of the object and the horizontal surface remain the same.

    A The object and surface will be pushing into each other less and so the normal force on the object will decrease.
    B It will be easier for the object to slide because the coefficient of friction between the object and the surface will decrease.
    C The object and surface will be pushing into each other more and so the normal force on the object will increase.
    D It will be harder for the object to slide because the coefficient of friction between the object and the surface will increase.
    Answer:

    If the object is covered with a thin layer of smoother material, the magnitude of the kinetic frictional force will .

    This is because of Reason .


ID is: 3677 Seed is: 454

Factors affecting kinetic friction

A box is sliding along a rough horizontal surface.

As the box slides, it experiences the kinetic frictional force (fโ†’k). Various properties of the box and the surface will affect this force, but some will not.

  1. For each property below, decide whether it does or does not affect the magnitude of the kinetic frictional force experienced by the box.

    Answer:

    The magnitude of the kinetic frictional force is affected by:

    • the material the box is made from:
    • the speed of box:
    • the material the surface is made from:
  2. The surface is covered with a thin layer of smoother material. Will the magnitude of the kinetic frictional force increase, decrease, or remain the same?

    Select a reason for your answer from the table of reasons given below. Assume that all other properties of the box and the horizontal surface remain the same.

    A The box and surface will be pushing into each other less and so the normal force on the box will decrease.
    B It will be harder for the box to slide because the coefficient of friction between the box and the surface will increase.
    C The box and surface will be pushing into each other more and so the normal force on the box will increase.
    D It will be easier for the box to slide because the coefficient of friction between the box and the surface will decrease.
    Answer:

    If the surface is covered with a thin layer of smoother material, the magnitude of the kinetic frictional force will .

    This is because of Reason .



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Definition: tension

Define tension using the dropdown menus below.

Answer:

Tension is the magnitude of the that is exerted by of a rope, wire, or other similar object. The is directed the rope and the magnitude is the rope.


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Definition: tension

Define tension using the dropdown menus below.

Answer:

Tension is the magnitude of the that is exerted by of a rope, wire, or other similar object. The is directed the rope and the magnitude is the rope.



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Definitions: Coefficients of friction

Define the coefficient of kinetic friction using the dropdown menus below.

Answer:

The coefficient of kinetic friction (ฮผk) is defined as the the and experienced by an object in contact with a surface.

It is which means it . It depends on .


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Definitions: Coefficients of friction

Define the coefficient of static friction using the dropdown menus below.

Answer:

The coefficient of static friction (ฮผs) is defined as the the and experienced by an object in contact with a surface.

It is which means it . It depends on .



ID is: 3328 Seed is: 6128

Definitions: Frictional forces

There are several different types of frictional force in mechanics.

Define maximum static frictional force using the dropdown menus below.

Answer:

The maximum static frictional force (fโ†’s max) is the force that the relative motion between a object and a surface. This force acts the surface.


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Definitions: Frictional forces

There are several different types of frictional force in mechanics.

Define frictional force using the dropdown menus below.

Answer:

The frictional force (fโ†’ or Fโ†’f) is the force that the relative motion between a object and a surface. This force acts the surface.



ID is: 3456 Seed is: 8946

The normal force on a slope

Iminathi is investigating the motion of a box as it slides up a rough wooden ramp.

The following free-body diagram shows all the forces exerted on the box.

Iminathi now increases ฮฑ, the angle of the ramp.

Will the magnitude of the normal force experienced by the box increase, decrease, or remain the same? Give a reason for your answer.

Answer:

The magnitude of the normal force will .

This is because increasing the angle of the ramp will the magnitude of the normal force.


ID is: 3456 Seed is: 1519

The normal force on a slope

Richard is investigating the motion of a box as it slides down a rough wooden ramp.

The following force diagram shows all the forces exerted on the box.

Richard now increases ฮฑ, the angle of the ramp.

Will the magnitude of the normal force experienced by the box increase, decrease, or remain the same? Give a reason for your answer.

Answer:

The magnitude of the normal force will .

This is because increasing the angle of the ramp will the magnitude of the normal force.



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Understanding fk=ฮผkFN

The relationship fk=ฮผkFN is an important equation in mechanics.

  1. What does the symbol fk stand for?

    Answer:

    The symbol fk stands for the .

  2. What is the SI unit used to measure FN?

    Answer:

    The SI unit used to measure FN is .


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Understanding fsmax=ฮผsFN

The relationship fsmax=ฮผsFN is a useful equation in mechanics.

  1. What does the symbol FN represent?

    Answer:

    The symbol FN represents the .

  2. What is the SI unit in which we measure ฮผs?

    Answer:

    The SI unit in which we measure ฮผs is .



ID is: 3458 Seed is: 4261

The normal force on a horizontal surface

Nnenna is investigating the motion of a crate as it slides to the left along a rough horizontal surface.

The following force diagram shows all the forces exerted on the crate.

Nnenna now pushes the crate perpendicularly into the surface.

Will the magnitude of the normal force increase, decrease, or remain the same? Give a reason for your answer.

Answer:

The magnitude of the normal force will .

This is because pushing the crate perpendicularly into the surface will the magnitude of the force the crate exerts perpendicularly into the surface.


ID is: 3458 Seed is: 1561

The normal force on a horizontal surface

Louise is investigating the motion of a box as it slides to the left along a rough horizontal surface.

The following free-body diagram shows all the forces exerted on the box.

Louise now pulls the box to the left parallel to the surface.

Will the magnitude of the normal force increase, decrease, or remain the same? Give a reason for your answer.

Answer:

The magnitude of the normal force will .

This is because pulling the box parallel to the surface will the magnitude of the force the box exerts perpendicularly into the surface.



ID is: 3676 Seed is: 7413

Factors affecting kinetic friction

A box is sliding down a rough slope.

As the box slides, it experiences the kinetic frictional force (fโ†’k). Various properties of the box and the slope will affect this force, but some will not.

  1. For each property below, decide whether it does or does not affect the magnitude of the kinetic frictional force experienced by the box.

    Answer:

    The magnitude of the kinetic frictional force is affected by:

    • the angle of inclination of the slope:
    • the distance travelled by the box:
    • the material the box is made from:
  2. The box is covered with a thin layer of rougher material. Will the magnitude of the kinetic frictional force increase, decrease, or remain the same?

    Select a reason for your answer from the table of reasons given below. Assume that all other properties of the box and the slope remain the same.

    A The box and the slope will be pushing into each other less and so the normal force on the box will decrease.
    B The box and the slope will be pushing into each other more and so the normal force on the box will increase.
    C It will be easier for the box to slide because the coefficient of friction between the box and the slope will decrease.
    D It will be harder for the box to slide because the coefficient of friction between the box and the slope will increase.
    Answer:

    If the box is covered with a thin layer of rougher material, the magnitude of the kinetic frictional force would .

    This is because of Reason .


ID is: 3676 Seed is: 8213

Factors affecting kinetic friction

A box is sliding down a rough slope.

As the box slides, it experiences the kinetic frictional force (fโ†’k). Various properties of the box and the slope will affect this force, but some will not.

  1. For each property below, decide whether it does or does not affect the magnitude of the kinetic frictional force experienced by the box.

    Answer:

    The magnitude of the kinetic frictional force is affected by:

    • the material the slope is made from:
    • the material the box is made from:
    • the mass of the box:
  2. The box was replaced with a box of smaller mass. Will the magnitude of the kinetic frictional force increase, decrease, or remain the same?

    Select a reason for your answer from the table of reasons given below. Assume that all other properties of the box and the slope remain the same.

    A The box and the slope will be pushing into each other less and so the normal force on the box will decrease.
    B It will be easier for the box to slide because the coefficient of friction between the box and the slope will decrease.
    C It will be harder for the box to slide because the coefficient of friction between the box and the slope will increase.
    D The box and the slope will be pushing into each other more and so the normal force on the box will increase.
    Answer:

    If the box was replaced with a box of smaller mass, the magnitude of the kinetic frictional force would .

    This is because of Reason .



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The relationship between FN, ฮผk, and fk

The normal force (FN), the coefficient of kinetic friction (ฮผk), and the kinetic frictional force (fk) are three important quantities in mechanics.

Which one of the following equations correctly represents the relationship between these quantities?

A fk=ฮผkFN
B fk=ฮผkFN
C fk=FNฮผk
Answer:

The correct equation is:


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The relationship between ฮผs, FN, and fsmax

The coefficient of static friction (ฮผs), the normal force (FN), and the maximum static frictional force (fsmax) are three important quantities in mechanics.

Which one of the following equations correctly represents the relationship between these quantities?

A ฮผs=FNfsmax
B ฮผs=FNfsmax
C ฮผs=fsmaxFN
Answer:

The correct equation is:



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Comparing types of friction

Objects can experience different forms of the frictional force: static friction, maximum static friction, and kinetic friction.

In the question below there is a list of four facts about each of these forces. Each list is missing two pieces of information. Complete the lists by selecting the correct choices.

Answer:

Static friction (fโ†’s)

  • experienced by a object
  • does not have a formula
  • depend on the roughness of the surfaces in contact
  • does depend on other forces parallel to the surface

Maximum static friction (fโ†’smax)

  • experienced by a object
  • does have a formula
  • depend on the roughness of the surfaces in contact
  • does not depend on other forces parallel to the surface

Kinetic friction (fโ†’k)

  • experienced by a object
  • does have a formula
  • depend on the roughness of the surfaces in contact
  • does not depend on other forces parallel to the surface

ID is: 3691 Seed is: 2088

Comparing types of friction

Objects can experience different forms of the frictional force: static friction, maximum static friction, and kinetic friction.

In the question below there is a list of four facts about each of these forces. Each list is missing two pieces of information. Complete the lists by selecting the correct choices.

Answer:

Static friction (fโ†’s)

  • experienced by a stationary object
  • does not have a formula
  • depend on the roughness of the surfaces in contact
  • depend on other forces parallel to the surface

Maximum static friction (fโ†’smax)

  • experienced by a stationary object
  • does have a formula
  • depend on the roughness of the surfaces in contact
  • depend on other forces parallel to the surface

Kinetic friction (fโ†’k)

  • experienced by a moving object
  • does have a formula
  • depend on the roughness of the surfaces in contact
  • depend on other forces parallel to the surface


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What type of friction is acting?

A box has been placed on a ramp. The ramp is at an angle such that the box is just about to slide down the ramp. If the angle were increased even by a small amount, the box would start to slide down the ramp.

What specific type of frictional force is involved in the above scenario?

Answer:

There is involved in the scenario.


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What type of friction is acting?

A plain wooden chair lies abandoned in a flat school corridor.

What specific type of frictional force is involved in the above scenario?

Answer:

There is involved in the scenario.

3. Newton's laws

4. Frictional forces



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Friction and the normal force on a horizontal surface

Babalwe is investigating the motion of an object as it slides to the right along a rough horizontal surface.

The following force diagram shows all the forces exerted on the object.

Babalwe now pushes on the object with a force that is angled into the surface to the right.

Will the magnitude of the kinetic frictional force experienced by the object increase, decrease, or remain the same? Give a reason for your answer.

Answer:

The magnitude of the kinetic frictional force will .

This is because pushing on the object with a force that is angled into the surface will the magnitude of the force the object exerts perpendicularly into the surface.


ID is: 3457 Seed is: 4561

Friction and the normal force on a horizontal surface

Amirah is investigating the motion of a box as it slides to the right along a rough horizontal surface.

The following free-body diagram shows all the forces exerted on the box.

Amirah now pulls on the box with a force that is angled out of the surface to the right.

Will the magnitude of the kinetic frictional force experienced by the box increase, decrease, or remain the same? Give a reason for your answer.

Answer:

The magnitude of the kinetic frictional force will .

This is because pulling on the box with a force that is angled out of the surface will the magnitude of the force the box exerts perpendicularly into the surface.



ID is: 3455 Seed is: 136

Friction and the normal force on a slope

Akeju is investigating the motion of a box as it slides down a rough wooden ramp.

The following force diagram shows all the forces exerted on the box.

Akeju now increases ฮฑ, the angle of the ramp.

Will the magnitude of the kinetic frictional force experienced by the box increase, decrease, or remain the same? Give a reason for your answer.

Answer:

The magnitude of the kinetic frictional force will .

This is because increasing the angle of the ramp will the magnitude of the normal force.


ID is: 3455 Seed is: 6147

Friction and the normal force on a slope

Tlali is investigating the motion of a crate as it slides down a rough wooden ramp.

The following force diagram shows all the forces exerted on the crate.

Tlali now decreases ฮฑ, the angle of the ramp.

Will the magnitude of the kinetic frictional force experienced by the crate increase, decrease, or remain the same? Give a reason for your answer.

Answer:

The magnitude of the kinetic frictional force will .

This is because decreasing the angle of the ramp will the magnitude of the normal force.



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Working with the coefficient of kinetic friction

A box is sliding across a rough surface. The coefficient of kinetic friction between the surface and the box (ฮผk) is 0,204. The magnitude of the kinetic frictional force (fk) is 82,2 N.

What is the magnitude of the normal force (FN)?

INSTRUCTION: Round your answer to two decimal places.
Answer:

FN= N

one-of
type(numeric.abserror(0.01))

ID is: 1429 Seed is: 5686

Working with the coefficient of kinetic friction

A box is sliding across a rough surface. The coefficient of kinetic friction between the surface and the box (ฮผk) is 0,228. The magnitude of the kinetic frictional force (fk) is 109 N.

What is the magnitude of the normal force (FN)?

INSTRUCTION: Round your answer to two decimal places.
Answer:

FN= N

one-of
type(numeric.abserror(0.01))


ID is: 1430 Seed is: 1663

Working with the coefficient of static friction

A box is at rest on a rough surface. The coefficient of static friction between the surface and the box (ฮผs) is 0,61. The magnitude of the maximum static frictional force (fsmax) is 100 N.

What is the magnitude of the normal force (FN)?

INSTRUCTION: Round your answer to two decimal places.
Answer:

FN= N

one-of
type(numeric.abserror(0.01))

ID is: 1430 Seed is: 5955

Working with the coefficient of static friction

A box is at rest on a rough surface. It experiences a normal force of magnitude 631 N. The magnitude of the maximum static frictional force (fsmax) is 403,8 N.

What is the coefficient of static friction (ฮผs)?

INSTRUCTION: Round your answer to two decimal places.
Answer:

ฮผs=

one-of
type(numeric.abserror(0.01))


ID is: 3549 Seed is: 8599

Friction and getting an object to start moving

Erioluwa applies a pulling force to a crate that is initially at rest on a rough horizontal surface. The force that Erioluwa applies is parallel to the surface.

The paragraphs below describe how the frictional force changes as Erioluwa pulls harder. Use the drop-down menus below to complete the paragraphs.

Answer:

Before Erioluwa starts pulling on the stationary crate, it experiences zero frictional force.

As she starts to pull on the stationary crate it experiences a static frictional force. As Erioluwa increases the magnitude of the force with which she pulls, the crate remains stationary, and the magnitude of the frictional force until it reaches its value, called maximum static friction.

When the magnitude of the pulling force is maximum static friction, the crate is stationary, but just about to start moving. When Erioluwa pulls with a force greater than maximum static friction, the crate starts to move and it will experience a frictional force. The magnitude of the kinetic frictional force is the maximum static frictional force.


ID is: 3549 Seed is: 3491

Friction and getting an object to start moving

Chukwuma applies a pulling force to a bookshelf that is initially at rest on a rough horizontal surface. The force that Chukwuma applies is parallel to the surface.

The paragraphs below describe how the frictional force changes as Chukwuma pulls harder. Use the drop-down menus below to complete the paragraphs.

Answer:

Before Chukwuma starts pulling on the stationary bookshelf, it experiences zero frictional force.

As he starts to pull on the stationary bookshelf it experiences a static frictional force. As Chukwuma increases the magnitude of the force with which he pulls, the bookshelf remains stationary, and the magnitude of the frictional force until it reaches its biggest possible value, called friction.

When the magnitude of the pulling force is maximum static friction, the bookshelf is stationary, but just about to start moving. When Chukwuma pulls with a force greater than maximum static friction, the bookshelf starts to move and it will experience a frictional force. The magnitude of the kinetic frictional force is the maximum static frictional force.



ID is: 3560 Seed is: 9532

What is friction?

Khayalethu shoves a crate across a rough floor. He observes the crate slow down as it slides across the rough floor.

Khayalethu's friend, Phetoho, makes four statements about the nature of the frictional force that acts on the crate.

  1. The kinetic frictional force is directly proportional to the normal force acting on the crate.
  2. The frictional force comes from the electrostatic force.
  3. The frictional force depends on the speed of the crate.
  4. The frictional force arises from tiny bumps in both surfaces which opposes relative motion.

Help Khayalethu classify each of these statements as true or false.

Answer:

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What is friction?

Werner shoves a crate across a rough floor. He observes the crate slow down as it slides across the rough floor.

Werner's friend, Werner, makes four statements about the nature of the frictional force that acts on the crate.

  1. The kinetic frictional force is directly proportional to the normal force acting on the crate.
  2. The frictional force comes from the electrostatic force.
  3. The frictional force arises from tiny bumps in both surfaces which opposes relative motion.
  4. The frictional force is directly proportional to the size of the contact area between the two surfaces

Help Werner classify each of these statements as true or false.

Answer:


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Factors affecting kinetic friction: horizontal

Two crates are sliding along two horizontal surfaces.

The crates are identical. The only difference between the two surfaces is that Surface A is made from a rougher material than Surface B.

Which crate will experience the smaller frictional force? Select a reason for your answer from the table below.

A lower roughness...

A increases the normal force.
B decreases the normal force.
C increases the coefficient of kinetic friction.
D decreases the coefficient of kinetic friction.
E does not change either the normal force or the coefficient of kinetic friction.
Answer:

will experience the smaller frictional force. This is because a lower roughness .


ID is: 3693 Seed is: 4137

Factors affecting kinetic friction: horizontal

Two objects are sliding along two horizontal surfaces.

The only difference between the two objects is that Object A is made from a rougher material than Object B. The two horizontal surfaces are identical.

Which object will experience the smaller frictional force? Select a reason for your answer from the table below.

A lower roughness...

A increases the normal force.
B decreases the normal force.
C increases the coefficient of kinetic friction.
D decreases the coefficient of kinetic friction.
E does not change either the normal force or the coefficient of kinetic friction.
Answer:

will experience the smaller frictional force. This is because a lower roughness .



ID is: 3745 Seed is: 8542

Frictional forces

A block is at rest on the surface of a rough wooden desk. Chizoba pulls on the block and the block moves along the surface. The value of maximum static friction for the block and the table is 45 N. Below is the force diagram showing all forces acting on the block.

  1. After Chizoba starts pulling on the block, what type of frictional force does the block experience?
  2. What can we say about the magnitude of the frictional force exerted on the block?
Answer:
  1. The object experiences friction.
  2. The magnitude of the frictional force is N.

ID is: 3745 Seed is: 3542

Frictional forces

A box is at rest on the surface of a rough wooden desk. Hannah pulls on the box, but the box remains stationary. Hannah can tell that even if she pulled harder, it would still not move. The value of maximum static friction for the box and the table is 70 N. Below is the force diagram showing all forces acting on the box.

  1. After Hannah starts pulling on the box, what type of frictional force does the box experience?
  2. What can we say about the magnitude of the frictional force exerted on the box?
Answer:
  1. The object experiences friction.
  2. The magnitude of the frictional force is N.


ID is: 3343 Seed is: 2876

Factors affecting kinetic friction

Two crates are sliding down inclined planes.

The only difference between the two crates is that Crate A is made from a smoother material than Crate B. The two inclined planes are identical.

Which crate will experience the greater frictional force? Give a reason for your answer.

Answer:

will experience the greater frictional force. This is because a greater .


ID is: 3343 Seed is: 7317

Factors affecting kinetic friction

Two objects are sliding down inclined planes.

The objects are identical. The only difference between the two inclined planes is that Plane A is made from a smoother material than Plane B.

Which object will experience the greater frictional force? Give a reason for your answer.

Answer:

will experience the greater frictional force. This is because a greater .



ID is: 3660 Seed is: 1471

Proportional reasoning with fsmax, ฮผs, and FN

The relationship fsmax=ฮผsFN is an important equation in mechanics.

fsmax is the maximum static frictional force, ฮผs is the coefficient of static friction, and FN is the normal force.

  1. For a fixed coefficient of static friction, what can we say about the relationship between the maximum static frictional force and the normal force?

    Answer:

    The maximum static frictional force is the normal force.

  2. Consider the options below and choose the one that represents the relationship between the maximum static frictional force and the normal force symbolically:

    A fsmax>FN
    B fsmax<FN
    C fsmaxโˆ1FN
    D fsmax=FN
    E fsmaxโˆFN
    Answer:

    The correct option is .

  3. Consider two scenarios in which the same object is pushed into the same surface by different amounts. The normal force of the object in the second scenario is 7 times bigger than the normal force of the object in the first scenario.

    How does the maximum static frictional force in the second scenario compare to the maximum static frictional force in the first scenario?

    Answer:

    The maximum static frictional force in the second scenario is the maximum static frictional force in the first scenario.


ID is: 3660 Seed is: 6538

Proportional reasoning with fsmax, ฮผs, and FN

The relationship fsmax=ฮผsFN is an important equation in mechanics.

fsmax is the maximum static frictional force, ฮผs is the coefficient of static friction, and FN is the normal force.

  1. For a fixed normal force, what can we say about the relationship between the maximum static frictional force and the coefficient of static friction?

    Answer:

    The maximum static frictional force is the coefficient of static friction.

  2. Consider the options below and choose the one that represents the relationship between the maximum static frictional force and the coefficient of static friction symbolically:

    A fsmax=ฮผs
    B fsmax<ฮผs
    C fsmaxโˆฮผs
    D fsmax>ฮผs
    E fsmaxโˆ1ฮผs
    Answer:

    The correct option is .

  3. Consider two scenarios involving the same object on two different surfaces (the normal force is constant). The coefficient of static friction for the second scenario is 6 times smaller than the coefficient of static friction in the first scenario.

    How does the maximum static frictional force in the second scenario compare to the maximum static frictional force in the first scenario?

    Answer:

    The maximum static frictional force in the second scenario is the maximum static frictional force in the first scenario.



ID is: 1550 Seed is: 6085

Coefficients of friction

A toy truck weighing 74 N is placed on a rough, flat surface and a rope is tied to it. The tension in the rope can be increased to 34,3 N before the truck starts to slide. A force of 29,4 N will keep the truck moving at constant speed once it has been set in motion. Determine the coefficients of static and kinetic friction.

INSTRUCTION: Round your answers to two decimal places.
Answer:

ฮผs=
ฮผk=

one-of
type(numeric.abserror(0.01))
one-of
type(numeric.abserror(0.01))

ID is: 1550 Seed is: 1877

Coefficients of friction

A block of wood weighing 66 N is placed on a rough, flat surface and a rope is tied to it. The tension in the rope can be increased to 34,9 N before the block starts to slide. A force of 26,5 N will keep the block moving at constant speed once it has been set in motion. Determine the coefficients of static and kinetic friction.

INSTRUCTION: Round your answers to two decimal places.
Answer:

ฮผs=
ฮผk=

one-of
type(numeric.abserror(0.01))
one-of
type(numeric.abserror(0.01))


ID is: 3744 Seed is: 4380

Experiment: Friction and the normal force

Musa and Songezo perform an experiment to determine the relationship between the normal force and the maximum static frictional force.

They use the following method in their experiment:

  1. Connect a spring balance to a block of known mass using a string.
  2. Place this block on a wooden surface.
  3. Pull on the spring balance until the block just starts to move.
  4. Record the reading on the spring balance. This is the magnitude of the applied pulling force (Fpull).
  5. Add a known mass piece on top of the block. This will change the normal force.
  6. Repeat Steps 3 - 5 until you have five pairs of data.
  1. Which one of the following is the independent variable in their experiment?

    A the normal force
    B the magnitude of the pulling force
    C the tension in the string
    D the table surface used
    Answer:

    The independent variable is:

  2. Musa pulls on the spring balance and Songezo records the force. They produce the following table of results of the magnitude of the applied pulling force (Fpull) for a given system mass (M).

    M(kg) Fpull(N)
    0,57 2,6
    0,67 2,7
    0,77 3,1
    0,87 3,7
    0,97 4,2

    Determine the following when the mass of the system is 0,97 kg:

    1. The magnitude of the normal force experienced by the system.
    2. The magnitude of the maximum static frictional force experienced by the system.
    INSTRUCTION:
    • Round both of your final answers to one decimal place.
    • Use the values given here for any physical constants that you may need.
    Answer:

    When the mass of the system is 0,97 kg:

    1. FN=
    2. fsmax=
    numeric
    numeric
  3. In a scientific experiment we need to work with the data before we draw a conclusion.

    Musa and Songezo decide that they need to use their data to determine a best estimate for the coefficient of static friction.

    1. Because they expect ฮผs to be constant, one way to get this estimate is to determine the arithmetic mean (average). Use all the data points to calculate the average value of the coefficient of static friction.

      INSTRUCTION: Round your answer to two decimal places.
    2. Which other method could be used to determine a best estimate for ฮผs?

      A Calculate the gradient of a graph of the normal force plotted against the maximum static frictional force
      B Calculate the gradient of a graph of the maximum static frictional force plotted against the normal force.
      C Calculate the y-intercept of a graph of the maximum static frictional force plotted against the normal force.
      D Calculate the y-intercept of a graph of the normal force plotted against the maximum static frictional force.
    3. Help Musa and Songezo draw a suitable conclusion for their experiment.

      W The material of the block is inversely proportional to the applied pulling force.
      X The mass of the system is inversely proportional to the tension in the string.
      Y The maximum static frictional force is directly proportional to the normal force.
      Z The tension in the string is directly proportional to the coefficient of maximum static friction.
    Answer:
    1. ฮผs,avg=
    2. Another method to get the best estimate of ฮผs is to:
    3. Musa and Songezo can conclude that:
    numeric

ID is: 3744 Seed is: 3727

Experiment: Friction and the normal force

Nnenne and Anthea perform an experiment to determine the relationship between the normal force and the kinetic frictional force.

They use the following method in their experiment:

  1. Connect a spring balance to a block of known mass using a string.
  2. Place this block on a wooden surface.
  3. Pull on the spring balance so that the block moves with a constant velocity.
  4. Record the reading on the spring balance. This is the magnitude of the applied pulling force (Fpull).
  5. Add a known mass piece on top of the block. This will change the normal force.
  6. Repeat Steps 3 - 5 until you have five pairs of data.
  1. Which one of the following is a fixed variable in their experiment?

    A the tension in the string
    B the magnitude of the pulling force
    C the coefficient of kinetic friction
    D the mass of the system
    Answer:

    A fixed variable is:

  2. Nnenne pulls on the spring balance and Anthea records the force. They produce the following table of results of the magnitude of the applied pulling force (Fpull) for a given system mass (M).

    M(kg) Fpull(N)
    0,49 1,2
    0,59 1,5
    0,69 1,9
    0,79 2,0
    0,89 2,3

    Determine the following when the mass of the system is 0,89 kg:

    1. The magnitude of the normal force experienced by the system.
    2. The magnitude of the kinetic frictional force experienced by the system.
    INSTRUCTION:
    • Round both of your final answers to one decimal place.
    • Use the values given here for any physical constants that you may need.
    Answer:

    When the mass of the system is 0,89 kg:

    1. FN=
    2. fk=
    numeric
    numeric
  3. In a scientific experiment we need to work with the data before we draw a conclusion.

    Nnenne and Anthea decide that they need to use their data to determine a best estimate for the coefficient of kinetic friction.

    1. Because they expect ฮผk to be constant, one way to get this estimate is to determine the arithmetic mean (average). Use all the data points to calculate the average value of the coefficient of kinetic friction.

      INSTRUCTION: Round your answer to two decimal places.
    2. Which other method could be used to determine a best estimate for ฮผk?

      A Calculate the gradient of a graph of the kinetic frictional force plotted against the normal force.
      B Calculate the y-intercept of a graph of the normal force plotted against the kinetic frictional force.
      C Calculate the y-intercept of a graph of the kinetic frictional force plotted against the normal force.
      D Calculate the gradient of a graph of the normal force plotted against the kinetic frictional force
    3. Help Nnenne and Anthea draw a suitable conclusion for their experiment.

      W The coefficient of kinetic friction is inversely proportional to the tension in the string.
      X The mass of the system is inversely proportional to the applied pulling force.
      Y The kinetic frictional force is directly proportional to the coefficient of kinetic friction.
      Z The kinetic frictional force is directly proportional to the normal force.
    Answer:
    1. ฮผk,avg=
    2. Another method to get the best estimate of ฮผk is to:
    3. Nnenne and Anthea can conclude that:
    numeric


ID is: 3688 Seed is: 5372

The friction graph and force diagrams

Chinonso applies a pushing force to a table that is initially at rest on a rough horizontal surface. The force that Chinonso applies is parallel to the surface.

Chinonso gradually increases the magnitude of the pushing force.

The following is a graph of the magnitude of the frictional force (f) experienced by the table plotted against the magnitude of the applied pushing force (Fpush).

The graph shows the relationship between the two parallel forces experienced by the box. The force diagram below is also a way of representing the relationship between the parallel forces at a given point.

Match the force diagram with a label from the graph (A - D).

Answer:

The given force diagram matches .


ID is: 3688 Seed is: 9887

The friction graph and force diagrams

Lefu applies a pushing force to a table that is initially at rest on a rough horizontal surface. The force that Lefu applies is parallel to the surface.

Lefu gradually increases the magnitude of the pushing force.

The following is a graph of the magnitude of the frictional force (f) experienced by the table plotted against the magnitude of the applied pushing force (Fpush).

The graph shows the relationship between the two parallel forces experienced by the box. The force diagram below is also a way of representing the relationship between the parallel forces at a given point.

Match the force diagram with a label from the graph (W - Z).

Answer:

The given force diagram matches .



ID is: 3692 Seed is: 5075

MCQ: Factors affecting kinetic friction

Two objects are sliding down two slopes.

Object A on Slope A

Object B on Slope B

There are only two differences.

  1. Object A is higher on the slope than Object B.
  2. Object A has a smaller contact area with the slope than Object B.

Which object will experience the greater kinetic frictional force?

A Object A
B Object B
C Neither object
D Impossible to tell
Answer:

The correct option is:


ID is: 3692 Seed is: 7828

MCQ: Factors affecting kinetic friction

Two crates are sliding down two slopes.

Crate A on Slope A

Crate B on Slope B

There are only two differences.

  1. Slope A is inclined at a smaller angle to the horizontal than Slope B.
  2. Slope A is made from a smoother material than Slope B.

Which crate will experience the greater kinetic frictional force?

A Crate A
B Crate B
C Neither crate
D Impossible to tell
Answer:

The correct option is:



ID is: 4565 Seed is: 8334

How the normal force affects friction

Adapted from DBE Nov 2015 Grade 11, P1, Q3
Physical constants ยท Physics formulas

A block of mass m is placed on a rough horizontal surface. A constant force (Fโ†’) pulls the block, but the block remains at rest as shown in the diagram below. The coefficient of static friction between the block and the surface is ฮผs. If the magnitude of the applied force were any larger, the block would begin to move.

The force is changed to one of the same magnitude but in the direction shown in the diagram below. The block and rough surface stay the same.

Describe what will happen to the block. Give a reason for your answer.

Answer:

The block will ...

This is because the normal force ...


ID is: 4565 Seed is: 3909

How the normal force affects friction

Adapted from DBE Nov 2015 Grade 11, P1, Q3
Physical constants ยท Physics formulas

A block of mass m is placed on a rough horizontal surface. A constant force (Fโ†’) pulls the block and the block moves across the surface at a constant speed as shown in the diagram below. The coefficient of kinetic friction between the block and the surface is ฮผk.

The force is changed to one of the same magnitude but in the direction shown in the diagram below. The block and rough surface stay the same.

Describe what will happen to the block. Give a reason for your answer.

Answer:

The block will ...

This is because the normal force ...



ID is: 3687 Seed is: 9061

The story of the friction graph

Nthofeela applies a pulling force to a box that is initially at rest on a rough horizontal surface. The force that Nthofeela applies is parallel to the surface.

The following is a graph of the magnitude of the frictional force (f) experienced by the box plotted against the magnitude of the applied pulling force (Fpull).

Graphs tell stories! The table below tells the story of the graph in four parts, but in the wrong order. Match each part of the story with a label from the graph (P - S).

Answer:
The magnitude of the static frictional force reaches its largest possible value, called maximum static friction. When the magnitude of the pulling force is equal to maximum static friction, the box is stationary, but just about to start moving.
When Nthofeela pulls with a force greater than maximum static friction, the box starts to move and it will experience a kinetic frictional force. The magnitude of the kinetic frictional force is less than the maximum static frictional force. It is independent of the size of the pulling force.
Before Nthofeela starts pulling on the stationary box, it experiences zero frictional force.
Once Nthofeela starts to pull on the stationary box it experiences a static frictional force. As he increases the magnitude of the force with which he pulls, the box remains stationary, and the magnitude of the static frictional force increases.

ID is: 3687 Seed is: 9074

The story of the friction graph

Latifah applies a pulling force to a box that is initially at rest on a rough horizontal surface. The force that Latifah applies is parallel to the surface.

The following is a graph of the magnitude of the frictional force (f) experienced by the box plotted against the magnitude of the applied pulling force (Fpull).

Graphs tell stories! The table below tells the story of the graph in four parts, but in the wrong order. Match each part of the story with a label from the graph (S - V).

Answer:
Once Latifah starts to pull on the stationary box it experiences a static frictional force. As she increases the magnitude of the force with which she pulls, the box remains stationary, and the magnitude of the static frictional force increases.
When Latifah pulls with a force greater than maximum static friction, the box starts to move and it will experience a kinetic frictional force. The magnitude of the kinetic frictional force is less than the maximum static frictional force. It is independent of the size of the pulling force.
Before Latifah starts pulling on the stationary box, it experiences zero frictional force.
The magnitude of the static frictional force reaches its largest possible value, called maximum static friction. When the magnitude of the pulling force is equal to maximum static friction, the box is stationary, but just about to start moving.


ID is: 3765 Seed is: 2872

Experiment: Determining the coefficient of static friction

Sarah performs an investigation to find out the coefficient of static friction for various materials when in contact with wood.

She makes use of a block sliding down an inclined plane. The block is covered in various materials: paper, waxpaper, cellophane, sandpaper, and tinfoil.

This is the method she follows from her textbook:

  1. Measure the length of the plank of wood.
  2. Cover the bottom of the block with one of the materials.
  3. Place the block near one edge of the plank.
  4. Slowly increase the angle of the plank until the block just begins to move. Measure the critical height (hc) of the block when it just starts to move using a metre-rule.
  5. Use trigonometry to determine the critical angle (ฮฑc). This is the angle at which the block will just begin to move.
  6. Hence determine the coefficient of static friction using ฮผs=tanโก(ฮฑc).
  7. Complete Steps 2 - 6 for all the different block coverings you will be investigating.

The following diagram shows the experimental setup:

  1. Sarah measured the length of the plank to be 1,040 m. She obtains the following heights for each block covering:

    Covering Height (m)
    paper 0,47
    waxpaper 0,44
    cellophane 0,24
    sandpaper 0,66
    tinfoil 0,38

    Determine the critical angle (ฮฑc) when the block was covered with tinfoil.

    Hence determine the coefficient of static friction for tinfoil on wood.

    INSTRUCTION: Round both of your final answers to two decimal places.
    Answer:

    When the block is covered with tinfoil:

    • ฮฑc= ยฐ
    • ฮผs=
    numeric
    numeric
  2. Which covering has the third lowest coefficient of static friction?

    Answer:

    The covering with the third lowest ฮผs is .

  3. The following table contains various statements relating to the experiment.

    A Several different height readings for the same block covering should be taken.
    B The critical angle is higher for block coverings with higher coefficients of static friction.
    C It might be difficult to hold the plank steady when measuring the height.
    D Smoother surfaces have fewer irregularities in their surface that can interlock with each other. This reduces the electrostatic force of attraction between surface atoms which makes it is easier for surfaces to start sliding past each other.

    Match an appropriate statement from the above table (A - D) to each of the following:

    1. A possible conclusion for the experiment.
    2. A factor that may add to the uncertainty in the results of the experiment.
    3. Something that will improve the results of the experiment.
    Answer:
    1. : a possible conclusion for the experiment.
    2. : a factor that may add to the uncertainty in the results of the experiment.
    3. : something that will improve the results of the experiment.

ID is: 3765 Seed is: 5776

Experiment: Determining the coefficient of static friction

Fezekile performs an investigation to find out the coefficient of static friction for various materials when in contact with wood.

He makes use of a block sliding down an inclined plane. The block is covered in various materials: sandpaper, waxpaper, cardboard, paper, and tinfoil.

This is the method he follows from his textbook:

  1. Measure the length of the plank of wood.
  2. Cover the bottom of the block with one of the materials.
  3. Place the block near one edge of the plank.
  4. Slowly increase the angle of the plank until the block just begins to move. Measure the critical height (hc) of the block when it just starts to move using a metre-rule.
  5. Use trigonometry to determine the critical angle (ฮฑc). This is the angle at which the block will just begin to move.
  6. Hence determine the coefficient of static friction using ฮผs=tanโก(ฮฑc).
  7. Complete Steps 2 - 6 for all the different block coverings you will be investigating.

The following diagram shows the experimental setup:

  1. Fezekile measured the length of the plank to be 1,610 m. He obtains the following heights for each block covering:

    Covering Height (m)
    sandpaper 1,00
    waxpaper 0,65
    cardboard 0,77
    paper 0,70
    tinfoil 0,61

    Determine the critical angle (ฮฑc) when the block was covered with sandpaper.

    Hence determine the coefficient of static friction for sandpaper on wood.

    INSTRUCTION: Round both of your final answers to two decimal places.
    Answer:

    When the block is covered with sandpaper:

    • ฮฑc= ยฐ
    • ฮผs=
    numeric
    numeric
  2. Which covering has the second highest coefficient of static friction?

    Answer:

    The covering with the second highest ฮผs is .

  3. The following table contains various statements relating to the experiment.

    A How you judge when the block starts to move needs to be done consistently.
    B Smoother surfaces have fewer irregularities in their surface that can interlock with each other. This reduces the electrostatic force of attraction between surface atoms which makes it is easier for surfaces to start sliding past each other.
    C The height at which the block starts to slide is higher for block coverings with higher coefficients of static friction.
    D The plank of wood used as the inclined plane might not be perfectly uniform.

    Match an appropriate statement from the above table (A - D) to each of the following:

    1. Something that will improve the results of the experiment.
    2. A factor that may add to the uncertainty in the results of the experiment.
    3. An explanation of an observed trend, using theory.
    Answer:
    1. : something that will improve the results of the experiment.
    2. : a factor that may add to the uncertainty in the results of the experiment.
    3. : an explanation of an observed trend, using theory.


ID is: 3690 Seed is: 4518

Maximum static friction and the critical angle of a slope

A wooden crate is at rest on a rough slope which is inclined at an angle ฮฑ to the horizontal.

  1. Write down expressions for the components of the gravitational force parallel and perpendicular to the slope.

    Use any of the following variables and trigonometric functions in your answers:

    mgฮฑsincostan
    INSTRUCTIONS:
    • you can type a for the symbol ฮฑ
    • put a space before trigonometric functions and brackets around the input angle e.g. type b tan(a) for btanโกฮฑ
    Answer:

    Fg,โˆฅ=

    Fg,โŠฅ=

    The component of the gravitational force has the same magnitude as the normal force, FN.

    one-of
    type(expression)
    one-of
    type(expression)
  2. The angle of the incline is gradually increased until the crate is just about to start sliding down the slope. This angle, ฮฑc, is the critical angle of the slope. If this angle were any greater the component of the gravitational force parallel to the slope would exceed the maximum static frictional force and the crate would start to slide down the slope.

    The following is a derivation of the relationship between the coefficient of static friction and the critical angle of the slope:

    ฮผs=tanโก(ฮฑc)

    Study the derivation and answer the questions that follow.

    Derivation

    We will take "up the slope" as the positive direction:

    StepNo.fโ†’smax+Fโ†’g,โˆฅ=Fโ†’net,โˆฅ(1)fโ†’smax+Fโ†’g,โˆฅ=0(2)ฮผsFN+Fโ†’g,โˆฅ=0(3)ฮผsFNโˆ’mgsinโก(ฮฑc)=0(4)ฮผsmgcosโก(ฮฑc)=mgsinโก(ฮฑc)(5)ฮผscosโก(ฮฑc)=sinโก(ฮฑc)(6)โˆดฮผs=tanโก(ฮฑc)(7)

    The following seven statements are explanations of how one step of the derivation follows from the previous step. However, the explanations are in the incorrect order!

    A

    Use the formula for maximum static friction

    fsmax=ฮผsFN
    B

    Substitute the component of the gravitational force parallel to the slope at the critical angle

    Fg,โˆฅ=mgsinโก(ฮฑc)
    C

    Substitute the normal force at the critical angle

    FN=mgcosโก(ฮฑc)

    and add mgsinโก(ฮฑc) to both sides of the equation.

    D

    Divide both sides by cosโก(ฮฑc) and then use the trigonometric identity

    tanโก(ฮฑc)=sinโก(ฮฑc)cosโก(ฮฑc)
    E

    Divide both sides by mg.

    F

    Use the definition of net force, Fโ†’net, as the vector sum of all forces parallel to the slope.

    G

    Use Newton's second law for an object in static equilibrium

    Fโ†’net=0

    Match each step in the derivation (1 to 7) with the correct explanation (A to G). Three of the steps have been done for you.

    Answer:
    1. fโ†’smax+Fโ†’g,โˆฅ=Fโ†’net,โˆฅ
      (Explanation F)
    2. fโ†’smax+Fโ†’g,โˆฅ=0
    3. ฮผsFN+Fโ†’g,โˆฅ=0
    4. ฮผsFNโˆ’mgsinโก(ฮฑc)=0
    5. ฮผsmgcosโก(ฮฑc)=mgsinโก(ฮฑc)
      (Explanation C)
    6. ฮผscosโก(ฮฑc)=sinโก(ฮฑc)
    7. โˆดฮผs=tanโก(ฮฑc)
      (Explanation D)

ID is: 3690 Seed is: 657

Maximum static friction and the critical angle of a slope

A plastic box is at rest on a rough plank which is inclined at an angle ฮฑ to the horizontal.

  1. Write down expressions for the components of the gravitational force parallel and perpendicular to the plank.

    Use any of the following variables and trigonometric functions in your answers:

    mgฮฑsincostan
    INSTRUCTIONS:
    • you can type a for the symbol ฮฑ
    • put a space before trigonometric functions and brackets around the input angle e.g. type b tan(a) for btanโกฮฑ
    Answer:

    Fg,โˆฅ=

    Fg,โŠฅ=

    The component of the gravitational force has the same magnitude as the normal force, FN.

    one-of
    type(expression)
    one-of
    type(expression)
  2. The angle of the incline is gradually increased until the box is just about to start sliding down the plank. This angle, ฮฑc, is the critical angle of the plank. If this angle were any greater the component of the gravitational force parallel to the plank would exceed the maximum static frictional force and the box would start to slide down the plank.

    The following is a derivation of the relationship between the coefficient of static friction and the critical angle of the plank:

    ฮผs=tanโก(ฮฑc)

    Study the derivation and answer the questions that follow.

    Derivation

    We will take "up the plank" as the positive direction:

    StepNo.fโ†’smax+Fโ†’g,โˆฅ=Fโ†’net,โˆฅ(1)fโ†’smax+Fโ†’g,โˆฅ=0(2)ฮผsFN+Fโ†’g,โˆฅ=0(3)ฮผsFNโˆ’mgsinโก(ฮฑc)=0(4)ฮผsmgcosโก(ฮฑc)=mgsinโก(ฮฑc)(5)ฮผscosโก(ฮฑc)=sinโก(ฮฑc)(6)โˆดฮผs=tanโก(ฮฑc)(7)

    The following seven statements are explanations of how one step of the derivation follows from the previous step. However, the explanations are in the incorrect order!

    A

    Use the definition of net force, Fโ†’net, as the vector sum of all forces parallel to the slope.

    B

    Divide both sides by cosโก(ฮฑc) and then use the trigonometric identity

    tanโก(ฮฑc)=sinโก(ฮฑc)cosโก(ฮฑc)
    C

    Use Newton's second law for an object in static equilibrium

    Fโ†’net=0
    D

    Use the formula for maximum static friction

    fsmax=ฮผsFN
    E

    Divide both sides by mg.

    F

    Substitute the normal force at the critical angle

    FN=mgcosโก(ฮฑc)

    and add mgsinโก(ฮฑc) to both sides of the equation.

    G

    Substitute the component of the gravitational force parallel to the slope at the critical angle

    Fg,โˆฅ=mgsinโก(ฮฑc)

    Match each step in the derivation (1 to 7) with the correct explanation (A to G). Three of the steps have been done for you.

    Answer:
    1. fโ†’smax+Fโ†’g,โˆฅ=Fโ†’net,โˆฅ
      (Explanation A)
    2. fโ†’smax+Fโ†’g,โˆฅ=0
    3. ฮผsFN+Fโ†’g,โˆฅ=0
    4. ฮผsFNโˆ’mgsinโก(ฮฑc)=0
      (Explanation G)
    5. ฮผsmgcosโก(ฮฑc)=mgsinโก(ฮฑc)
    6. ฮผscosโก(ฮฑc)=sinโก(ฮฑc)
      (Explanation E)
    7. โˆดฮผs=tanโก(ฮฑc)


ID is: 3689 Seed is: 268

Graphing friction

Jessica applies a pulling force to a table that is initially at rest on a rough horizontal surface. The force that Jessica applies is parallel to the surface.

The following is a graph of the magnitude of the frictional force experienced by the table plotted against the magnitude of the applied pulling force.

Match each of the descriptions in the table below with the correct label in the graph (P - T).

Answer:
the magnitude of the pulling force
the static frictional force matches the applied pulling force
the kinetic frictional force is independent of the applied pulling force
the frictional force experienced by the table
the table is just about to move

ID is: 3689 Seed is: 313

Graphing friction

Matlhodi applies a pushing force to a couch that is initially at rest on a rough horizontal surface. The force that Matlhodi applies is parallel to the surface.

The following is a graph of the magnitude of the frictional force experienced by the couch plotted against the magnitude of the applied pushing force.

Match each of the descriptions in the table below with the correct label in the graph (J - N).

Answer:
the magnitude of the pushing force
the range of the applied force for which the couch is moving
the magnitude of the frictional force
the couch is just about to move
the range of the applied force for which the couch is stationary

5. Force and free-body diagrams



ID is: 3327 Seed is: 1243

Definitions: Force and free-body diagrams

Define a free-body diagram using the dropdown menus below.

Answer:

A free-body diagram shows the of all forces exerted on an object using to represent the force vectors. The object is represented by and all force vectors have their tails at the and point .


ID is: 3327 Seed is: 7719

Definitions: Force and free-body diagrams

Define a force diagram using the dropdown menus below.

Answer:

A force diagram shows the of all forces exerted on an object using to represent the force vectors. The object is represented by and all force vectors have their tails at the and point .



ID is: 3518 Seed is: 1735

Free-body and force diagrams

A number of different forces are acting on a suitcase. Chiamaka draws the following diagram to show all these forces.

Did Chiamaka draw a free-body diagram or a force diagram?

Give a reason for your answer from the table below.

A the object is represented by an outline of the actual shape of the object with each force acting on the object drawn as an arrow pointing away from the point on the object at which the force acts
B the object is represented by a dot with each force acting on the object drawn as an arrow pointing away from the dot
Answer:

Chiamaka drew a diagram.

We know this because .


ID is: 3518 Seed is: 1472

Free-body and force diagrams

A number of different forces are acting on a box. Talatu draws the following diagram to show all these forces.

Did Talatu draw a free-body diagram or a force diagram?

Give a reason for your answer from the table below.

A the object is represented by a dot with each force acting on the object drawn as an arrow pointing away from the dot
B the object is represented by an outline of the actual shape of the object with each force acting on the object drawn as an arrow pointing away from the point on the object at which the force acts
Answer:

Talatu drew a diagram.

We know this because .



ID is: 3615 Seed is: 5664

Multiple choice: Matching free-body diagrams to objects

A block of mass m1 is connected to another block of mass m2 by a light inextensible string. This system of blocks is then suspended from the ceiling by the top block, using the same type of string.

  1. Draw labelled free-body diagrams indicating all the forces acting on each block.

    Now compare your diagrams to the two diagrams given below and answer the questions that follow.

    Diagram A

    Diagram B

    1. Which diagram is the free-body diagram for the bottom block?
    2. Which force does Force Qโ†’ represent?
    Answer:
    1. Diagram is the free-body diagram for the bottom block.
    2. Force Qโ†’ represents the force acting on the block.

ID is: 3615 Seed is: 1755

Multiple choice: Matching free-body diagrams to objects

A block of mass m1 is connected to another block of mass m2 by a light inextensible rope. This system of blocks is then suspended from the ceiling by the top block, using the same type of rope.

  1. Draw labelled free-body diagrams indicating all the forces acting on each block.

    Now compare your diagrams to the two diagrams given below and answer the questions that follow.

    Diagram A

    Diagram B

    1. Which diagram is the free-body diagram for the top block?
    2. Which force does Force Yโ†’ represent?
    Answer:
    1. Diagram is the free-body diagram for the top block.
    2. Force Yโ†’ represents the force acting on the block.


ID is: 3671 Seed is: 1611

Identifying number of forces acting on systems on inclined planes

Block 1 is connected to Block 2 by a light inextensible rope. The same type of rope is attached to Block 2, run over a light frictionless pulley, and connected to a motor.

The motor pulls the system up a smooth plane inclined at an angle ฮฑ to the horizontal. The motor applies a constant force which causes the system to accelerate. The force applied by the motor is parallel to the plane as shown in the diagram below. Ignore all forms of friction.

Draw labelled free-body diagrams indicating all the forces acting on the both blocks.

How many forces should there be in these diagrams?Remember that a free-body diagram should contain actual forces, not components of forces.

Answer:
  1. There is/are force(s) in the free-body diagram for the bottom block.
  2. There is/are force(s) in the free-body diagram for the top block.
one-of
type(string)
one-of
type(string)

ID is: 3671 Seed is: 8990

Identifying number of forces acting on systems on inclined planes

Box 1 is connected to Box 2 by a light inextensible cable. The same type of cable is attached to Box 2, run over a light frictionless pulley, and connected to a motor.

The motor pulls the system up a smooth plane inclined at an angle ฮฑ to the horizontal. The motor applies a constant force which causes the system to accelerate. The force applied by the motor is parallel to the plane as shown in the diagram below. Ignore all forms of friction.

Draw labelled free-body diagrams representing all the forces acting on the both boxes.

How many forces should there be in these diagrams?Remember that a free-body diagram should contain actual forces, not components of forces.

Answer:
  1. There is/are force(s) in the free-body diagram for the bottom box.
  2. There is/are force(s) in the free-body diagram for the top box.
one-of
type(string)
one-of
type(string)


ID is: 3667 Seed is: 4635

Mistakes in free-body diagrams!

Box 1 is connected to Box 2 by a light inextensible rope. The system is pulled up a smooth slope inclined at ฮฑ to the horizontal, by means of a constant force parallel to the slope as shown in the diagram below. All forms of friction can be ignored.

Draw a labelled free-body diagram showing all the forces acting on Box 1 as it moves up the slope.

The free-body diagram given below contains a mistake. There is a problem with one of the forces.

Compare your free-body diagram to the given diagram to work out which force is the problem and what the mistake is.

Possible mistakes
1 The force is missing.
2 The force has the wrong direction.
3 The force should not be there.
Answer:

The force with the problem is the force.

The problem is .


ID is: 3667 Seed is: 7423

Mistakes in free-body diagrams!

Box 1 is connected to Box 2 by a light inextensible string. The system is pulled up a rough plane inclined at ฮฑ to the horizontal, by means of a constant force parallel to the plane as shown in the diagram below. The magnitude of the kinetic frictional force between the surface and Box 1 is fk,1.

Draw a labelled free-body diagram indicating all the forces acting on Box 1 as it moves up the plane.

The free-body diagram given below contains a mistake. There is a problem with one of the forces.

Compare your free-body diagram to the given diagram to work out which force is the problem and what the mistake is.

Possible mistakes
1 The force is missing.
2 The force has the wrong direction.
3 The force should not be there.
Answer:

The force with the problem is the force.

The problem is .



ID is: 3895 Seed is: 110

Force and free-body diagrams: systems

A system of two crates is pulled up a smooth ramp.

The string joining the two crates is inextensible (it can't be stretched) and it is pulled tight.

Xolile draws a diagram to show all the forces acting on one of the crates.

This is the diagram that she draws:

Which one of the options below best describes the diagram that Xolile drew?

A A free-body diagram for the higher crate.
B A force diagram for the lower crate.
C A free-body diagram for the lower crate.
D A force diagram for the higher crate.
Answer:

The correct choice is:


ID is: 3895 Seed is: 4722

Force and free-body diagrams: systems

A system of two crates is pulled up a rough inclined plane.

The cord joining the two crates is inextensible (it can't be stretched) and it is pulled tight.

Tlali draws a diagram to show all the forces acting on one of the crates.

This is the diagram that he draws:

Which one of the options below best describes the diagram that Tlali drew?

A A force diagram for the higher crate.
B A free-body diagram for the higher crate.
C A free-body diagram for the lower crate.
D A force diagram for the lower crate.
Answer:

The correct choice is:



ID is: 4566 Seed is: 6404

Free-body diagrams on a rough horizontal surface

Adapted from DBE Nov 2015 Grade 11, P1, Q3
Physical constants ยท Physics formulas

A 20 kg block is placed on a rough horizontal surface. A constant force (Fโ†’) pushes the block and the block moves across the surface at a constant speed as shown in the diagram below. The coefficient of kinetic friction (ฮผk) between the block and the surface is 0,42.

Draw a labelled free-body diagram showing all the forces acting on the block.

For each of the free-body diagrams below use the table of options (W to Z) to say if the diagram is correct or to explain why it is incorrect.

Answer:
Options
W The diagram is correct!
X The frictional force is missing.
Y The normal force has the wrong direction.
Z The frictional force has the wrong direction.

Diagram I

Diagram II

Diagram III

Diagram IV


ID is: 4566 Seed is: 4569

Free-body diagrams on a rough horizontal surface

Adapted from DBE Nov 2015 Grade 11, P1, Q3
Physical constants ยท Physics formulas

A 45 kg block is placed on a rough horizontal surface. A constant force (Fโ†’) pushes the block, but the block remains at rest as shown in the diagram below. The coefficient of static friction (ฮผs) between the block and the surface is 0,57. If the magnitude of the applied force were any larger, the block would begin to move.

Draw a labelled free-body diagram showing all the forces acting on the block.

For each of the free-body diagrams below use the table of options (W to Z) to say if the diagram is correct or to explain why it is incorrect.

Answer:
Options
W The diagram is correct!
X The normal force has the wrong length.
Y The frictional force has the wrong direction.
Z The applied force is in the wrong direction.

Diagram I

Diagram II

Diagram III

Diagram IV



ID is: 3894 Seed is: 6080

Getting force and free-body diagrams right!

A string is used to hang a charged insulated sphere from the ceiling. An electrostatic force repels the charged sphere to the right. The sphere is in static equilibrium.

Phozisa draws the following free-body diagram to show all the forces acting on the charged sphere.

The diagram has the correct number of forces, but one of the forces is pointing in the wrong direction. Which force is incorrect?

A Tโ†’
B Fโ†’g
C Fโ†’elec
Answer:

The force pointing in the wrong direction is:


ID is: 3894 Seed is: 977

Getting force and free-body diagrams right!

A system of two crates is pulled up a rough inclined plane.

Jabulile draws the following force diagram to show all the forces acting on the higher crate.

The diagram has the correct number of forces, but one of the forces is pointing in the wrong direction. Which force is incorrect?

A Fโ†’g
B Tโ†’
C fโ†’
D Fโ†’pull
E Fโ†’N
Answer:

The force pointing in the wrong direction is:



ID is: 3800 Seed is: 8548

Getting force and free-body diagrams right!

A crate is pushed to the left across a rough surface.

Chidinma tries to draw a force diagram to show all the forces acting on the crate.

This is the diagram that she draws:

The diagram has the correct number of forces, but there is a problem with the diagram! What mistake did Chidinma make?

A The forces have not been labelled.
B The forces have incorrect arrowheads.
C A free-body diagram was drawn instead of a force diagram.
D The tail of at least one force vector is in the wrong place.
Answer:

The mistake made was:


ID is: 3800 Seed is: 3802

Getting force and free-body diagrams right!

An object is in a lift which is moving down at constant velocity.

Adeboye tries to draw a free-body diagram to show all the forces acting on the object.

This is the diagram that he draws:

The diagram has the correct number of forces, but there is a problem with the diagram! What mistake did Adeboye make?

A The tail of at least one force vector is in the wrong place.
B One of the forces is pointing in the wrong direction.
C A force diagram was drawn instead of a free-body diagram.
D The forces have incorrect arrowheads.
Answer:

The mistake made was:

6. Components and resultants of forces



ID is: 1428 Seed is: 7247

Identifying vector components

Consider the following diagram of a bus parked on a hill:

Choose the vector which best describes the frictional force acting on the bus.

A Fโ†’up D Fโ†’down
B Fโ†’โŠฅ,up E Fโ†’โŠฅ,down
C Fโ†’โˆฅ,left F Fโ†’โˆฅ,right
Answer:

ID is: 1428 Seed is: 1654

Identifying vector components

Consider the following diagram of a car parked on a hill:

Choose the vector which best describes the gravitational force acting on the car.

A Fโ†’up D Fโ†’down
B Fโ†’โŠฅ,up E Fโ†’โŠฅ,down
C Fโ†’โˆฅ,left F Fโ†’โˆฅ,right
Answer:


ID is: 1427 Seed is: 8223

Resolving the gravitational force into components

A gravitational force of Fโ†’g=196 N is acting straight down on a block. The block is on an inclined plane with a slope inclined at an angle of 34ยฐ with the horizontal.

Calculate the components of the force due to gravity parallel and perpendicular to the slope.

INSTRUCTION: Round your answers to one decimal place.
Answer:

Fโ†’g,โˆฅ= N

Fโ†’g,โŠฅ= N

numeric
numeric

ID is: 1427 Seed is: 4575

Resolving the gravitational force into components

A gravitational force of Fโ†’g=171 N is acting straight down on a block. The block is on an inclined plane with a slope inclined at an angle of 31ยฐ with the horizontal.

Calculate the components of the force due to gravity parallel and perpendicular to the slope.

INSTRUCTION: Round your answers to one decimal place.
Answer:

Fโ†’g,โˆฅ= N

Fโ†’g,โŠฅ= N

numeric
numeric


ID is: 3773 Seed is: 5040

Adding vector force components

Five forces are acting on an object. The following diagram shows the scenario as seen from the side.

Three of the forces are aligned along the vertical axis. The other two forces are aligned along the horizontal axis.

Calculate:

  1. The net force along the vertical axis.
  2. The net force along the horizontal axis.
INSTRUCTIONS:
  • Give the magnitudes of both components to the nearest newton.
  • Use the drop-down menus to show the directions or to indicate if there is no direction.
Answer:
  1. Fโ†’net,vertical= N .
  2. Fโ†’net,horizontal= N .
numeric
numeric

ID is: 3773 Seed is: 8046

Adding vector force components

Five forces are acting on an object. The following diagram shows the scenario as seen from the side.

Three of the forces are aligned along the vertical axis. The other two forces are aligned along the horizontal axis.

Calculate:

  1. The net force along the vertical axis.
  2. The net force along the horizontal axis.
INSTRUCTIONS:
  • Give the magnitudes of both components to the nearest newton.
  • Use the drop-down menus to show the directions or to indicate if there is no direction.
Answer:
  1. Fโ†’net,vertical= N .
  2. Fโ†’net,horizontal= N .
numeric
numeric


ID is: 3670 Seed is: 5370

Identifying the correct expression

Box 1 is connected to Box 2 by a light inextensible cable. The same type of cable is attached to Box 2, run over a light frictionless pulley, and connected to a motor.

The motor pulls the system up a smooth plane inclined at an angle ฮฑ to the horizontal. The motor applies a constant force which causes the system to accelerate. The force applied by the motor is parallel to the plane as shown in the diagram below. Ignore all forms of friction.

The following table contains possible expressions for the magnitude of the net force experienced by the two crates. Identify which expression belongs with each crate.

W Fmotorโˆ’Tโˆ’m2gcosโกฮฑ
X Tโˆ’m1gsinโกฮฑ
Y Fmotorโˆ’Tโˆ’m2gsinโกฮฑ
Z Tโˆ’m1gcosโกฮฑ
Answer:
  1. The magnitude of the net force on the bottom box is given by .
  2. The magnitude of the net force on the top box is given by .

ID is: 3670 Seed is: 2821

Identifying the correct expression

Block 1 is connected to Block 2 by a light inextensible rope. The same type of rope is attached to Block 2, run over a light frictionless pulley, and connected to a motor.

The motor pulls the system up a smooth plane inclined at an angle ฮฑ to the horizontal. The motor applies a constant force which causes the system to accelerate. The force applied by the motor is parallel to the plane as shown in the diagram below. Ignore all forms of friction.

The following table contains possible expressions for the magnitude of the net force experienced by the two crates. Identify which expression belongs with each crate.

W Tโˆ’m1gsinโกฮฑ
X Tโˆ’m1gcosโกฮฑ
Y Fmotorโˆ’Tโˆ’m2gsinโกฮฑ
Z Fmotorโˆ’Tโˆ’m2gcosโกฮฑ
Answer:
  1. The magnitude of the net force on the bottom block is given by .
  2. The magnitude of the net force on the top block is given by .


ID is: 3748 Seed is: 4234

Vector components

Megan is pulling an object across the floor with a force of 150 N at an angle of 32ยฐ to the horizontal. The following diagram (which is not to scale) shows the scenario as seen from the side.

Resolve the pulling force into horizontal (x) and vertical (y) components.

INSTRUCTIONS:
  • Give magnitudes of the components.
  • Round both of your answers to two decimal places.
Answer:

The magnitudes of the components of the pulling force are:

Fx= N

Fy= N

one-of
type(numeric.abserror(0.01))
one-of
type(numeric.abserror(0.01))

ID is: 3748 Seed is: 2588

Vector components

Riaan is pulling a crate across the floor with a force of 280 N at an angle of 20ยฐ west of north. The following diagram (which is not to scale) shows the scenario as seen from above.

Resolve the pulling force into components to the north and west.

INSTRUCTIONS:
  • Give magnitudes of the components.
  • Round both of your answers to two decimal places.
Answer:

The magnitudes of the components of the pulling force are:

Fnorth= N

Fwest= N

one-of
type(numeric.abserror(0.01))
one-of
type(numeric.abserror(0.01))


ID is: 1493 Seed is: 9473

Resultant force

Akinlabi is pushing a trolley with a constant force of 61,65 N. The trolley is experiencing a force due to gravity of 151 N. A constant frictional force of 32,6 N is present.

What is the resultant force on the trolley?

INSTRUCTION: Round your answer to two decimal places.
Answer:

Fโ†’net= N

one-of
type(numeric.abserror(0.01))

ID is: 1493 Seed is: 5607

Resultant force

Mpho is pushing a trolley with a constant force of 65,75 N. The trolley is experiencing a force due to gravity of 155 N. A constant frictional force of 47,18 N is present.

What is the resultant force on the trolley?

INSTRUCTION: Round your answer to two decimal places.
Answer:

Fโ†’net= N

one-of
type(numeric.abserror(0.01))


ID is: 3746 Seed is: 8621

Vector components

Fadekemi is pulling a chest across the floor with a force Fโ†’ at an angle of 38ยฐ to the vertical. The following diagram (which is not to scale) shows the scenario as seen from the side.

The vertical component of the pulling force is 258 N.

Calculate:

  1. the magnitude of the applied pulling force.
  2. the magnitude of the horizontal component of the pulling force.
INSTRUCTION: Round both of your answers to two decimal places.
Answer:

F= N

Fx= N

one-of
type(numeric.abserror(0.01))
one-of
type(numeric.abserror(0.01))

ID is: 3746 Seed is: 8451

Vector components

Amy is pulling a block across the floor with a force Fโ†’ at an angle of 32ยฐ to the vertical. The following diagram (which is not to scale) shows the scenario as seen from the side.

The vertical component of the pulling force is 153 N.

Calculate:

  1. the magnitude of the applied pulling force.
  2. the magnitude of the horizontal component of the pulling force.
INSTRUCTION: Round both of your answers to two decimal places.
Answer:

F= N

Fx= N

one-of
type(numeric.abserror(0.01))
one-of
type(numeric.abserror(0.01))


ID is: 3747 Seed is: 3001

Vector components

Mike is pulling a block across the floor with a force Fโ†’ at an angle of ฮฑ north of west. The following diagram (which is not to scale) shows the scenario as seen from above.

The component of the pulling force to the west is 138 N and the component of the pulling force to the north is 111 N.

Calculate:

  1. the magnitude of the applied pulling force.
  2. the angle that describes the direction of the applied pushing force.
INSTRUCTION: Round both of your answers to two decimal places.
Answer:

F= N

ฮฑ= ยฐ

one-of
type(numeric.abserror(0.01))
one-of
type(numeric.abserror(0.01))

ID is: 3747 Seed is: 8665

Vector components

Hannah is pulling a crate across the floor with a force Fโ†’ at an angle of ฮฑ east of south. The following diagram (which is not to scale) shows the scenario as seen from above.

The component of the pulling force to the south is 233 N and the component of the pulling force to the east is 140 N.

Calculate:

  1. the magnitude of the applied pulling force.
  2. the angle that describes the direction of the applied pushing force.
INSTRUCTION: Round both of your answers to two decimal places.
Answer:

F= N

ฮฑ= ยฐ

one-of
type(numeric.abserror(0.01))
one-of
type(numeric.abserror(0.01))


ID is: 1437 Seed is: 4812

Resolving the gravitational force into components

A gravitational force of Fโ†’g=198 N is acting straight down on a block on an inclined slope.

If the magnitude of the component of the gravitational force perpendicular to the slope is 172,8 N, what is the incline (angle) of the slope as measured from the horizontal?

INSTRUCTION: Round your answer to one decimal place.
Answer: ฮธ= ยฐ
one-of
type(numeric.abserror(0.1))

ID is: 1437 Seed is: 2827

Resolving the gravitational force into components

A gravitational force of Fโ†’g=130 N is acting straight down on a block on an inclined slope.

If the magnitude of the component of the gravitational force parallel to the slope is 46,4 N, what is the incline (angle) of the slope as measured from the horizontal?

INSTRUCTION: Round your answer to one decimal place.
Answer: ฮธ= ยฐ
one-of
type(numeric.abserror(0.1))


ID is: 1501 Seed is: 6385

Resultants

Two forces, 10 N and 3 N, act at an angle at the same point.

Which one of the following cannot be the magnitude of the resultant of these two forces?

Answer:

ID is: 1501 Seed is: 570

Resultants

Two forces, 7 N and 3 N, act at an angle at the same point.

Which one of the following can be the magnitude of the resultant of these two forces?

Answer:


ID is: 3770 Seed is: 338

Adding vector force components

Five forces are acting on an object. The following diagram shows the scenario as seen from above.

Three of the forces are aligned along the east-west axis. The other two forces are aligned along the north-south axis.

Calculate the magnitude and direction of the net force exerted on the object.

INSTRUCTIONS:
  • Round both the magnitude and direction to two decimal places.
  • Specify the direction as an angle north of west.
Answer:

Fโ†’net= N at ยฐ north of west.

one-of
type(numeric.abserror(0.01))
one-of
type(numeric.abserror(0.01))

ID is: 3770 Seed is: 9726

Adding vector force components

Five forces are acting on a box. The following diagram shows the scenario as seen from above.

Three of the forces are aligned along the east-west axis. The other two forces are aligned along the north-south axis.

Calculate the magnitude and direction of the net force exerted on the box.

INSTRUCTIONS:
  • Round both the magnitude and direction to two decimal places.
  • Specify the direction as an angle south of west.
Answer:

Fโ†’net= N at ยฐ south of west.

one-of
type(numeric.abserror(0.01))
one-of
type(numeric.abserror(0.01))


ID is: 3524 Seed is: 6768

Components and inclined planes

Anathi is moving house. He is pushing a table with mass m down a ramp off the moving truck. The ramp is inclined at an angle ฮฑ to the horizontal. The force has a magnitude F and acts at an angle ฮฒ to the normal of the ramp as shown in the diagram below.

  1. Write down expressions for the magnitude of the perpendicular component of the pushing force (FโŠฅ) as well as the magnitude of the perpendicular component of the gravitational force (Fg,โŠฅ).

    TIP: Which components are calculated using cos and which are calculated using sin depends on the line from which the angle is measured (the horizontal, the vertical, from the normal of the ramp, from the ramp). Always go back to the definitions of the trig functions rather than trying to remember results like these.

    You can use any of the following variables and trigonometric functions in your answers:

    ฮฒ;m;ฮฑ;g;Fsin;cos;tan
    INSTRUCTIONS:
    • you can type a for the symbol ฮฑ
    • you can type B for the symbol ฮฒ
    • put brackets around the angle of the trigonometric function e.g. type tan(a) for tanโกฮฑ
    Answer:

    The perpendicular component of the pushing force:
    FโŠฅ=

    The perpendicular component of the gravitational force:
    Fg,โŠฅ=

    one-of
    type(expression)
    one-of
    type(expression)
  2. Anathi is pushing the table with a force of magnitude 230 N at an angle 67ยฐ to the normal of the ramp. The table has a mass 96 kg and the ramp is inclined at an angle 40ยฐ to the horizontal.

    Calculate the components of the pushing force and the gravitational force that are perpendicular to the ramp.

    INSTRUCTION: Round your answers to two decimal places.
    Answer:

    Fโ†’โŠฅ=
    Fโ†’g,โŠฅ=

    one-of
    type(numeric.abserror(0.01))
    numeric

ID is: 3524 Seed is: 1831

Components and inclined planes

Nyakallo is moving house. She is pushing a cupboard with mass m down a ramp off the moving truck. The ramp is inclined at an angle ฮฑ to the vertical. The force has a magnitude F and acts at an angle ฮฒ to the ramp as shown in the diagram below.

  1. Write down expressions for the magnitude of the perpendicular component of the pushing force (Fy) as well as the magnitude of the perpendicular component of the gravitational force (Fg,y).

    TIP: Which components are calculated using cos and which are calculated using sin depends on the line from which the angle is measured (the horizontal, the vertical, from the normal of the ramp, from the ramp). Always go back to the definitions of the trig functions rather than trying to remember results like these.

    You can use any of the following variables and trigonometric functions in your answers:

    m;g;ฮฒ;ฮฑ;Fcos;sin;tan
    INSTRUCTIONS:
    • you can type a for the symbol ฮฑ
    • you can type B for the symbol ฮฒ
    • put brackets around the angle of the trigonometric function e.g. type tan(a) for tanโกฮฑ
    Answer:

    The perpendicular component of the pushing force:
    Fy=

    The perpendicular component of the gravitational force:
    Fg,y=

    one-of
    type(expression)
    one-of
    type(expression)
  2. Nyakallo is pushing the cupboard with a force of magnitude 220 N at an angle 22ยฐ to the ramp. The cupboard has a mass 73 kg and the ramp is inclined at an angle 46ยฐ to the vertical.

    Calculate the components of the pushing force and the gravitational force that are perpendicular to the ramp.

    INSTRUCTION: Round your answers to two decimal places.
    Answer:

    Fโ†’y=
    Fโ†’g,y=

    one-of
    type(numeric.abserror(0.01))
    numeric

7. Newton's first law



ID is: 3641 Seed is: 7493

Definition: inertia

Define inertia, using the drop-down menus below.

Answer:

Inertia is the an object that causes it to its or .


ID is: 3641 Seed is: 7160

Definition: inertia

Define inertia, using the drop-down menus below.

Answer:

Inertia is the an object that causes it to its or .



ID is: 3642 Seed is: 2510

Statement: Newton's first law

Adapted from DBE Nov 2015 & 2016 Grade 11, P1, Q3
Physical constants ยท Physics formulas

State Newton's first law of motion in words.

Answer:

A body will remain in a state of or moving with unless a acts on it.


ID is: 3642 Seed is: 6431

Statement: Newton's first law

Adapted from DBE Nov 2015 & 2016 Grade 11, P1, Q3
Physical constants ยท Physics formulas

State Newton's first law of motion in words.

Answer:

A body will remain in a state of or moving with unless a is exerted on it.



ID is: 3789 Seed is: 4559

Buckle up!

Kutlwano is driving a car along a dirt road. A rabbit crosses the road and Kutlwano immediately slams on the brakes and manages to stop in time. Fortunately, Kutlwano was wearing a seatbelt and so was unharmed.

Use appropriate physics principles to complete the paragraph below which explains the importance of seatbelts.

Answer:

Initially, Kutlwano and the car are travelling at the same velocity. When the driver slams on the brakes, a net force is exerted on the car which causes it to slow down.

If Kutlwano were not strapped in with a seatbelt, she experience this net force. According to Newton's first law of motion, she would keep moving at the same velocity due to her inertia. She would be moving than the car. She would be flung relative to the car. She might go through the windscreen and get severe injuries.

But, because Kutlwano is strapped in with a seatbelt, the seatbelt apply a net force on her. This will cause her to with the car.


ID is: 3789 Seed is: 9755

Buckle up!

Ben is driving a car along a dirt road. A baboon crosses the road and Ben immediately slams on the brakes and manages to stop in time. Fortunately, Ben was wearing a seatbelt and so was unharmed.

Use appropriate physics principles to complete the paragraph below which explains the importance of seatbelts.

Answer:

Initially, Ben and the car are travelling at the same velocity. When the driver slams on the brakes, a net force is exerted on the car which causes it to slow down.

If Ben were not strapped in with a seatbelt, he experience this net force. According to Newton's first law of motion, he would keep moving at the same velocity due to his inertia. He would be moving than the car. He would be flung relative to the car. He might go through the windscreen and get severe injuries.

But, because Ben is strapped in with a seatbelt, the seatbelt apply a net force on him. This will cause him to with the car.



ID is: 4014 Seed is: 7118

Multiple choice: Newton's laws

Adapted from WCED Metro Central Sep 2017 Grade 12, P1, Q1.1
Physical constants ยท Physics formulas

If you don't walk carefully while holding a full cup of tea, the tea will easily spill over the edge of the cup because of ...

A acceleration and Newton's second law.
B gravity and Newton's universal law of gravitation.
C resistance to change in motion and Newton's first law.
D change in momentum and Newton's second law in terms of momentum.
Answer:

ID is: 4014 Seed is: 6411

Multiple choice: Newton's laws

Adapted from WCED Metro Central Sep 2017 Grade 12, P1, Q1.1
Physical constants ยท Physics formulas

If you don't walk carefully while holding a full cup of tea, the tea will easily spill over the edge of the cup because of ...

A resistance to change in motion and Newton's law of inertia.
B gravity and Newton's universal law of gravitation.
C momentum and Newton's second law in terms of momentum.
D acceleration and Newton's second law.
Answer:


ID is: 3767 Seed is: 211

MCQ: Newton's first law

A parcel is loose on the smooth back seat of a car. The driver of the car turns a corner sharply. The parcel is observed to slide to one side of the car.

Which one of the following statements could not be used as reason for why the parcel is observed to slide to the side?

A The parcel experiences a zero net force.
B The parcel has inertia and so resists a change in motion.
C The parcel keeps moving in the same direction, with the same speed.
D The influence of gravity on the parcel is reduced.
Answer: The incorrect reason is:

ID is: 3767 Seed is: 6309

MCQ: Newton's first law

A box is loose on the smooth back seat of a car. The driver of the car turns a corner sharply. The box is observed to slide to one side of the car.

Which one of the following statements could not be used as reason for why the box is observed to slide to the side?

A The box keeps moving in the same direction, with the same speed.
B The box experiences a zero net force.
C The box keeps moving at a constant velocity.
D The influence of gravity on the box is reduced.
Answer: The incorrect reason is:


ID is: 3768 Seed is: 5799

Falling for physics!

  1. Reabilwe is standing in a bus which is moving along a straight road. The bus suddenly speeds up. Reabilwe isn't holding onto anything and stumbles.

    In which direction will Reabilwe stumble?

    Answer:

    Reabilwe will stumble .

  2. Which one of the following gives the best reason why Reabilwe stumbles backward?

    A Her velocity remains constant.
    B It follows from Newton's third law of motion.
    C The floor of the bus exerts a net force on her.
    D Her inertia is conserved.
    Answer:

    The correct option is:


ID is: 3768 Seed is: 3328

Falling for physics!

  1. Thandolwethu is standing in a bus which is moving along a straight road. The bus suddenly changes speed. Thandolwethu isn't holding onto anything and stumbles forward.

    Did the bus speed up or slow down?

    Answer:

    The bus must have .

  2. Which one of the following gives the best reason why Thandolwethu stumbles forward?

    A Kinetic energy is always conserved.
    B It follows from Newton's first law of motion.
    C The floor of the bus exerts a net force on her.
    D Her inertia is conserved.
    Answer:

    The correct option is:



ID is: 3769 Seed is: 9986

Reasoning with Newton's first law

An object is loose on the smooth back seat of a car. The driver of the car turns a corner sharply. The object is observed to move to one side of the car.

Classify each of the following four statements as correct reasons or incorrect reasons for why the object is observed to move to the side.

Answer:
  1. The mass of the object is smaller than that of the car.
  2. The object keeps moving in the same direction, with the same speed.
  3. The influence of gravity on the object is reduced.
  4. The car has changed direction, but the object keeps moving in a straight line.

ID is: 3769 Seed is: 5468

Reasoning with Newton's first law

A box is loose on the smooth back seat of a car. The driver of the car turns a corner sharply. The box is observed to slide to one side of the car.

Classify each of the following four statements as correct reasons or incorrect reasons for why the box is observed to slide to the side.

Answer:
  1. The box keeps moving at a constant velocity.
  2. The box has inertia and so resists a change in motion.
  3. The influence of gravity on the box is reduced.
  4. The mass of the box is smaller than that of the car.


ID is: 3290 Seed is: 7981

Multiple choice: Newton's first law

Four different learners were asked to state what they thought Newtonโ€™s first law of motion means. Three of the learners have incorrect interpretations and one has a correct interpretation.

Which one of the following statements is correct?

A Objects change how they move because of their inertia.
B Only if no net force acts on an object will its motion remain constant.
C Objects tend to remain at rest which is the property of inertia.
D Objects resist being in motion which is why they slow down.
Answer:

The answer is: .


ID is: 3290 Seed is: 1918

Multiple choice: Newton's first law

Four different learners were asked to state what they thought Newtonโ€™s first law of motion means. Three of the learners have incorrect interpretations and one has a correct interpretation.

Which one of the following statements is correct?

A Objects move at a constant velocity only if they do not experience any forces.
B Objects resist being in motion which is why they slow down.
C Objects change how they move because of their inertia.
D Only if no net force acts on an object will its motion remain constant.
Answer:

The answer is: .



ID is: 3766 Seed is: 6222

MCQ: Falling for physics!

Phillip is standing in a moving train which suddenly speeds up. He isn't holding onto anything and falls backward!

Phillip falls backward because ...

A of Newton's third law of motion.
B he experiences a zero net force.
C of kinetic energy conservation.
D the floor of the train exerts a net force on him.
Answer: The correct option is:

ID is: 3766 Seed is: 9296

MCQ: Falling for physics!

Balarabe is standing in a stationary bus which suddenly starts to move. She isn't holding onto anything and falls backward!

Balarabe falls backward because ...

A of Newton's third law of motion.
B of kinetic energy conservation.
C of Newton's first law of motion.
D of conservation of inertia.
Answer: The correct option is:

8. Newton's second law



ID is: 3260 Seed is: 866

Statement: Newton's second law

Adapted from DBE Nov 2015 & 2016 Grade 11, P1, Q4
Physical constants ยท Physics formulas

State Newton's second law of motion in words.

Answer:

When a resultant force acts on an object, the object will the with the magnitude of the resultant force and the mass of the object.


ID is: 3260 Seed is: 1848

Statement: Newton's second law

Adapted from DBE Nov 2015 & 2016 Grade 11, P1, Q4
Physical constants ยท Physics formulas

State Newton's second law of motion in words.

Answer:

When is exerted on an object, the object will the with an acceleration the magnitude of the and inversely proportional to the mass of the object.



ID is: 3658 Seed is: 2952

Understanding Fnet=ma

The relationship Fnet=ma is an important equation in mechanics. It is the mathematical statement of Newton's second law of motion.

  1. What does the symbol m represent?

    Answer:

    The symbol m represents .

  2. What is the SI unit used to measure a?

    Answer:

    The SI unit used to measure a is .


ID is: 3658 Seed is: 2318

Understanding Fnet=ma

The relationship Fnet=ma is an important equation in mechanics. It is the mathematical statement of Newton's second law of motion.

  1. What does the symbol a represent?

    Answer:

    The symbol a represents .

  2. What is the SI unit used to measure Fnet?

    Answer:

    The SI unit used to measure Fnet is .



ID is: 3639 Seed is: 5770

The relationship between a, Fnet, and m

Acceleration (a), net force (Fnet), and mass (m) are three important quantities in mechanics. They are related to each other through Newton's second law of motion.

Which one of the following equations correctly represents the relationship between these quantities?

A m=Fneta
B m=aFnet
C m=aFnet
Answer:

The correct equation is:


ID is: 3639 Seed is: 3080

The relationship between m, Fnet, and a

Mass (m), net force (Fnet), and acceleration (a) are three important quantities in mechanics. They are related to each other through Newton's second law of motion.

Which one of the following equations correctly represents the relationship between these quantities?

A m=aFnet
B m=Fneta
C m=Fneta
Answer:

The correct equation is:



ID is: 1494 Seed is: 4907

Newton's second law of motion

A rickshaw is accelerated at 2,0 mยทsโˆ’2 by a net force of 294,0 N. Calculate the mass of the rickshaw.

INSTRUCTION: Round your answer to one decimal place.
Answer: m= kg
one-of
type(numeric.abserror(0.1))

ID is: 1494 Seed is: 4132

Newton's second law of motion

A canoe has a mass of 26 kg and accelerates at 0,3 mยทsโˆ’2. Calculate the magnitude of the resultant force that is causing the acceleration.

INSTRUCTION: Round your answer to one decimal place.
Answer: Fnet= N
one-of
type(numeric.abserror(0.1))


ID is: 1465 Seed is: 6568

Newton's second law

A rocket has a mass of 1,06ร—106 kg and experiences a force of 1,0388ร—107 N due to gravity. The rocket is accelerating at 11,98 mยทsโˆ’2.

  1. What is the resultant force acting on the rocket?

    INSTRUCTION: Write your answer in scientific notation and then round it to three decimal places.
    Answer:

    Fโ†’net= N

    numeric
  2. What driving force does the engine of the rocket need to exert on the rocket to maintain its acceleration?

    INSTRUCTION:
    • Use your unrounded answer from Question 1.
    • Write your answer in scientific notation and then round it to three decimal places.
    Answer:

    Fโ†’drive= N

    numeric

ID is: 1465 Seed is: 6040

Newton's second law

A space shuttle has a mass of 5,40ร—105 kg and experiences a force of 5,2920ร—106 N due to gravity. The space shuttle is ignited and is launched with a driving force of 2,139ร—107 N upwards.

  1. What is the resultant force acting on the space shuttle?

    INSTRUCTION: Write your answer in scientific notation and then round it to three decimal places.
    Answer:

    Fโ†’net= N

    numeric
  2. What is the acceleration of the space shuttle?

    INSTRUCTION:
    • Use your unrounded answer from Question 1.
    • Round your answer to two decimal places.
    Answer:

    aโ†’= mยทsโˆ’2

    one-of
    type(numeric.abserror(0.01))


ID is: 3657 Seed is: 2296

Proportional reasoning with Fnet, m, and a

The relationship Fnet=ma is an important equation in mechanics. It is the mathematical statement of Newton's second law of motion.

  1. For a fixed acceleration, what can we say about the relationship between net force and mass?

    Answer:

    Net force is mass.

  2. Consider the options below and choose the one that represents the relationship between net force and mass symbolically:

    A Fnet=m
    B Fnetโˆm
    C Fnetโˆ1m
    D Fnet>m
    E Fnet<m
    Answer:

    The correct option is .

  3. Consider two systems with the same acceleration. The net force of the second system is 8 times smaller than the net force of the first system. How does the mass of the second system compare to the mass of the first system?

    Answer:

    The mass of the second system will be the mass of the first system.


ID is: 3657 Seed is: 6235

Proportional reasoning with Fnet, m, and a

The relationship Fnet=ma is a useful equation in mechanics. It is the mathematical statement of Newton's second law of motion.

  1. For a constant mass, what can we say about the relationship between acceleration and net force?

    Answer:

    Acceleration is net force.

  2. Consider the options below and choose the one that represents the relationship between acceleration and net force symbolically:

    A a>Fnet
    B aโˆFnet
    C a=Fnet
    D aโˆ1Fnet
    E a<Fnet
    Answer:

    The correct option is .

  3. Consider two systems with the same mass. The acceleration of the second system is 6 times smaller than the acceleration of the first system. How does the net force of the second system compare to the net force of the first system?

    Answer:

    The net force of the second system will be the net force of the first system.



ID is: 3837 Seed is: 5130

Multiple choice: Newton's second law

Adapted from DBE Feb-Mar 2017 Grade 12, P1, Q1.1
Physical constants ยท Physics formulas

A group of learners exert different net forces on an object and cause it to accelerate.

According to Newton's second law of motion, the net force experienced by the object is __________ its acceleration.

A directly proportional to
B independent of
C inversely proportional to
D always equal to
Answer:

ID is: 3837 Seed is: 944

Multiple choice: Newton's second law

Adapted from DBE Feb-Mar 2017 Grade 12, P1, Q1.1
Physical constants ยท Physics formulas

A group of learners exert the same net force on different objects and cause them to accelerate.

According to Newton's second law of motion, the acceleration of each object is __________ its mass.

A inversely proportional to
B always less than
C directly proportional to
D independent of
Answer:


ID is: 4569 Seed is: 2406

Multiple choice: Proportionality with Newton's second law

Adapted from DBE Nov 2015 Grade 11, P1, Q1.3
Physical constants ยท Physics formulas

A net force with magnitude Fnet is exerted on an object of mass m and it causes an acceleration with a magnitude of a.

The same net force is applied to a different object. If the new object's mass is four times bigger than the mass of the first object, then the magnitude of the acceleration of the new object will be ...

A 14a
B a
C 4a
D 16a
Answer:

ID is: 4569 Seed is: 8258

Multiple choice: Proportionality with Newton's second law

Adapted from DBE Nov 2015 Grade 11, P1, Q1.3
Physical constants ยท Physics formulas

A net force with magnitude Fnet is exerted on an object of mass m and it causes an acceleration with a magnitude of a.

If the acceleration experienced by the object is four times smaller, then the magnitude of the net force that caused this must be ...

A 4Fnet
B 116Fnet
C Fnet
D 14Fnet
Answer:


ID is: 1467 Seed is: 5425

Applying Newton's second law

Ayodeji is pulling a 14 kg crate with a rope that makes an angle of 35ยฐ with the horizontal.

If he applies a force of magnitude 117 N and a frictional force of magnitude 41,2 N is present, calculate the acceleration of the crate.

INSTRUCTION:
  • Round your answer to two decimal places.
  • Use the values for any physical constants you might need, as listed here.
Answer: aโ†’= mยทsโˆ’2
one-of
type(numeric.abserror(0.01))

ID is: 1467 Seed is: 2779

Applying Newton's second law

Kelly is pulling a 19 kg box with a rope that makes an angle of 40ยฐ with the horizontal.

If she applies a force of magnitude 165 N and a frictional force of magnitude 18,6 N is present, calculate the acceleration of the box.

INSTRUCTION:
  • Round your answer to two decimal places.
  • Use the values for any physical constants you might need, as listed here.
Answer: aโ†’= mยทsโˆ’2
one-of
type(numeric.abserror(0.01))


ID is: 1562 Seed is: 89

Newton's second law

A person with a mass of 80 kg and a weight of 784 N stands on a scale (which gives a reading in newtons) inside a hot air balloon that is accelerating upwards at 3,2 mยทsโˆ’2. What is the reading on the scale?

INSTRUCTION: Round your answer to the nearest newton.
Answer:

The reading on the scale is N.

numeric

ID is: 1562 Seed is: 422

Newton's second law

A person with a mass of 90 kg and a weight of 882 N stands on a scale (which gives a reading in newtons) inside a hot air balloon that is accelerating downwards at 0,4 mยทsโˆ’2. What is the reading on the scale?

INSTRUCTION: Round your answer to the nearest newton.
Answer:

The reading on the scale is N.

numeric


ID is: 3825 Seed is: 3352

Forces with an object on a slope

Adapted from DBE Feb-Mar 2017 Grade 12, P1, Q2
Physical constants ยท Physics formulas

In the diagram below (not to scale), a small object of mass 6 kg is sliding at a constant velocity of 2,3 mยทsโˆ’1 down a rough plane inclined at 15ยฐ to the horizontal surface.

At the bottom of the plane, the object continues sliding onto the rough horizontal surface and eventually comes to a stop.

The coefficient of kinetic friction between the object and the surface is the same for both inclined surface and the horizontal surface.

INSTRUCTIONS:
  • Round all final numerical answers to two decimal places.
  • You must use these values for any physical constants required in your calculations.
  1. What is the magnitude of the net force acting on the object while it is on the slope?

    Answer: The magnitude of the net force is N.
    numeric
  2. Draw a labelled free-body diagram for the object while it is on the inclined plane. Then answer the questions that follow.

    Answer:
    1. How many forces are there in the free-body diagram?
    2. Friction is .
    3. There an applied force.
    numeric
  3. Calculate the:

    1. Magnitude of the frictional force acting on the object while it is sliding down the inclined plane.
    2. Coefficient of kinetic friction between the object and the surface.
    3. Distance the object travels on the horizontal surface before it comes to a stop.
    Answer:
    1. fk=
    2. ฮผk=
    3. ฮ”x=
    one-of
    type(numeric.abserror(0.1))
    one-of
    type(numeric.abserror(0.01))
    one-of
    type(numeric.abserror(0.01))

ID is: 3825 Seed is: 6663

Forces with an object on a slope

Adapted from DBE Feb-Mar 2017 Grade 12, P1, Q2
Physical constants ยท Physics formulas

In the diagram below (not to scale), a small object of mass 9 kg is sliding at a constant velocity of 3,5 mยทsโˆ’1 down a rough plane inclined at 22ยฐ to the horizontal surface.

At the bottom of the plane, the object continues sliding onto the rough horizontal surface and eventually comes to a stop.

The coefficient of kinetic friction between the object and the surface is the same for both inclined surface and the horizontal surface.

INSTRUCTIONS:
  • Round all final numerical answers to two decimal places.
  • You must use these values for any physical constants required in your calculations.
  1. What is the magnitude of the net force acting on the object while it is on the slope?

    Answer: The magnitude of the net force is N.
    numeric
  2. Draw a labelled free-body diagram for the object while it is on the inclined plane. Then answer the questions that follow.

    Answer:
    1. How many forces are there in the free-body diagram?
    2. Friction is .
    3. There an applied force.
    numeric
  3. Calculate the:

    1. Magnitude of the frictional force acting on the object while it is sliding down the inclined plane.
    2. Coefficient of kinetic friction between the object and the surface.
    3. Distance the object travels on the horizontal surface before it comes to a stop.
    Answer:
    1. fk=
    2. ฮผk=
    3. ฮ”x=
    one-of
    type(numeric.abserror(0.1))
    one-of
    type(numeric.abserror(0.01))
    one-of
    type(numeric.abserror(0.01))


ID is: 4568 Seed is: 1826

Multiple choice: Acceleration in a lift

Adapted from DBE Nov 2015 Grade 11, P1, Q1.4
Physical constants ยท Physics formulas

Ekene has a weight of 760 N. He is in an elevator (a lift) with a bathroom scale that gives a reading in newtons.

At some point while the elevator is getting faster, he looks at the scale and sees a reading of 700 N.

Which one of the following combinations correctly indicates the direction of motion of the elevator and the direction of the acceleration while the elevator is in motion?

Direction of motionDirection of acceleration
A downdown
B updown
C upup
D downup
Answer:

ID is: 4568 Seed is: 3896

Multiple choice: Acceleration in a lift

Adapted from DBE Nov 2015 Grade 11, P1, Q1.4
Physical constants ยท Physics formulas

Lisa has a weight of 730 N. She is in an elevator (a lift) with a bathroom scale that gives a reading in newtons.

At some point while the elevator is getting slower, she looks at the scale and sees a reading of 680 N.

Which one of the following combinations correctly indicates the direction of motion of the elevator and the direction of the acceleration while the elevator is in motion?

Direction of motionDirection of acceleration
A downup
B downdown
C upup
D updown
Answer:


ID is: 1469 Seed is: 2565

Forces in a lift

A student experiences a gravitational force of 774,2 N. He gets into a lift and steps onto a bathroom scale that is calibrated in newtons. When the lift is standing still the scale reads 774,2 N. When the student steps into the lift it is on floor 9.

He pushes the button to go to another floor. As the lift moves he notes that the reading on the scale changes during his ride. He records three stages in his journey:

  • Stage 1 โ†’ For 2 seconds immediately after the lift starts, the scale reads 703,1 N
  • Stage 2 โ†’ For a further 3 seconds it reads 774,2 N
  • Stage 3 โ†’ For the final 2 seconds it reads 845,3 N.
  1. Is the acceleration of the lift upward or downward in Stage 1?

    TIP: In a test or exam you will be required to give reasons for your answer.
    Answer:

    The direction of the acceleration in Stage 1 is .

  2. Calculate the resultant force acting on the student during Stage 3.

    INSTRUCTION:
    • Round your answer to one decimal place.
    • Select the direction using the drop-down menu.
    Answer:

    Fโ†’net= N

    one-of
    type(numeric.abserror(0.1))

ID is: 1469 Seed is: 9510

Forces in a lift

A student experiences a gravitational force of 1 029,0 N. He gets into a lift and steps onto a bathroom scale that is calibrated in newtons. When the lift is standing still the scale reads 1 029,0 N. When the student steps into the lift it is on floor 5.

He pushes the button to go to another floor. As the lift moves he notes that the reading on the scale changes during his ride. He records three stages in his journey:

  • Stage 1 โ†’ For 2 seconds immediately after the lift starts, the scale reads 913,5 N
  • Stage 2 โ†’ For a further 3 seconds it reads 1 029,0 N
  • Stage 3 โ†’ For the final 2 seconds it reads 1 144,5 N.
  1. Is the acceleration of the lift upward or downward in Stage 1?

    TIP: In a test or exam you will be required to give reasons for your answer.
    Answer:

    The direction of the acceleration in Stage 1 is .

  2. Calculate the resultant force acting on the student during Stage 1.

    INSTRUCTION:
    • Round your answer to one decimal place.
    • Select the direction using the drop-down menu.
    Answer:

    Fโ†’net= N

    one-of
    type(numeric.abserror(0.1))

9. Equilibrium and non-equilibrium



ID is: 3856 Seed is: 8736

Types of equilibrium

Consider the following scenario and answer the questions that follow.

Chidi connects a package to a light inextensible rope which is run over a light frictionless pulley. Chidi pulls on the rope, and the package accelerates up.

Is the package in equilibrium? If it is in equilibrium, what type of equilibrium? Give a reason for your answer.

Answer:

The package is equilibrium. We know this because it so the net force exerted on the package must be .


ID is: 3856 Seed is: 1784

Types of equilibrium

Consider the following scenario and answer the questions that follow.

Chinweike uses a cord to hang a charged insulated sphere from the ceiling. An electrostatic force pushes the charged sphere to the left. The sphere hangs without moving in the position shown in the diagram below.

Is the charged sphere in equilibrium? If it is in equilibrium, what type of equilibrium? Give a reason for your answer.

Answer:

The charged sphere is equilibrium. We know this because it so the net force exerted on the charged sphere must be .



ID is: 3854 Seed is: 3961

Equilibrium and diagrams

The following free-body diagram (to scale) shows all the forces exerted on an object.

  1. Is the object in equilibrium? Give a reason for your answer.

    Answer:

    The object in equilibrium. We know this because the net force exerted on the object is .


ID is: 3854 Seed is: 8201

Equilibrium and diagrams

The following free-body diagram (to scale) shows all the forces exerted on an object.

  1. Is the object in equilibrium? Give a reason for your answer.

    Answer:

    The object in equilibrium. We know this because the net force exerted on the object is .



ID is: 3811 Seed is: 8321

Normal force on a horizontal surface

A box is on a horizontal surface. Lidija pulls the box at an angle out of the surface with a force Fโ†’. The box remains in contact with the surface.

How does the magnitude of the normal force (FN) compare to the magnitude of the gravitational force (Fg)?

Answer:

FN is Fg.


ID is: 3811 Seed is: 9536

Normal force on a horizontal surface

A box is on a horizontal surface. Realeboha pushes the box straight down with a force Fโ†’.

How does the magnitude of the normal force (FN) compare to the magnitude of the gravitational force (Fg)?

Answer:

FN is Fg.



ID is: 3616 Seed is: 8757

Multiple choice: Vertical systems

A block of mass m1 is connected to another block of mass m2 by a light inextensible cable. This system of blocks is then suspended from the ceiling by the top block, using the same type of cable.

  1. The hanging system of blocks is in static equilibrium. What does this mean?

    A The system moves up and down around an equilibrium point.
    B The acceleration and velocity of the system are both zero.
    C The system is stationary because it experiences the static frictional force.
    D The Newton's third law action-reaction pairs all cancel each other out.
    Answer:

    The correct statement is .


ID is: 3616 Seed is: 1680

Multiple choice: Vertical systems

A block of mass m1 is connected to another block of mass m2 by a light inextensible string. This system of blocks is then suspended from the ceiling by the top block, using the same type of string.

  1. The hanging system of blocks is in static equilibrium. What does this mean?

    A The forces acting on the system are balanced and the system is stationary.
    B The system is stationary because it experiences the static frictional force.
    C The top block and the bottom block must have the same mass in order to be balanced.
    D The system gently swings from side to side.
    Answer:

    The correct statement is .



ID is: 3792 Seed is: 3287

Match the scenario to a force diagram

Consider the following scenario and answer the questions that follow.

Anuoluwapo connects a crate to a light inextensible rope which is run over a light frictionless pulley. Anuoluwapo pulls on the rope, but the crate moves down at a constant velocity.

  1. Is the crate in equilibrium? If it is in equilibrium, what type of equilibrium? Give a reason for your answer.

    Answer:

    The crate is equilibrium. We know this because it so the net force exerted on the crate must be .

  2. Which one of the following is the correct force diagram for the crate?

    TIP: Pay careful attention to scale. How long should the force vectors be compared to each other?
    A
    B
    C
    Answer:

    The correct diagram is:


ID is: 3792 Seed is: 8346

Match the scenario to a force diagram

Consider the following scenario and answer the questions that follow.

Chijindum places a crate in a lift which moves down at a constant velocity.

  1. Is the crate in equilibrium? If it is in equilibrium, what type of equilibrium? Give a reason for your answer.

    Answer:

    The crate is equilibrium. We know this because it so the net force exerted on the crate must be .

  2. Which one of the following is the correct force diagram for the crate?

    TIP: Pay careful attention to scale. How long should the force vectors be compared to each other?
    A
    B
    C
    Answer:

    The correct diagram is:



ID is: 3857 Seed is: 2860

Match the scenario to a free-body diagram

Consider the following scenario and answer the questions that follow.

Sarah uses a string to hang a charged insulated sphere from the ceiling. An electrostatic force pulls the charged sphere to the right. The sphere hangs without moving in the position shown in the diagram below.

  1. Is the charged sphere in equilibrium? If it is in equilibrium, what type of equilibrium? Give a reason for your answer.

    Answer:

    The charged sphere is equilibrium. We know this because it so the net force exerted on the charged sphere must be .

  2. Which one of the following is the correct free-body diagram for the charged sphere?

    TIP: Pay careful attention to scale. How long should the force vectors be compared to each other?
    A
    B
    C
    Answer:

    The correct diagram is:


ID is: 3857 Seed is: 5074

Match the scenario to a free-body diagram

Consider the following scenario and answer the questions that follow.

Justine connects an object to a light inextensible rope which is run over a light frictionless pulley. Justine pulls on the rope, and the object accelerates up.

  1. Is the object in equilibrium? If it is in equilibrium, what type of equilibrium? Give a reason for your answer.

    Answer:

    The object is equilibrium. We know this because it so the net force exerted on the object must be .

  2. Which one of the following is the correct free-body diagram for the object?

    TIP: Pay careful attention to scale. How long should the force vectors be compared to each other?
    A
    B
    C
    Answer:

    The correct diagram is:



ID is: 1495 Seed is: 3125

Resultant force

A donkey is trying to pull a cart with a constant force of 142 N. The cart experiences a force due to gravity of 2 244 N. The rope between the cart and the donkey makes an angle of 8ยฐ to the horizontal. The cart does not move.

Find the magnitude and direction of the frictional force preventing the cart from moving.

INSTRUCTION: Round your answer to two decimal places.
Answer:

Fโ†’friction= N

one-of
type(numeric.abserror(0.01))

ID is: 1495 Seed is: 1996

Resultant force

A mule is trying to pull a cart with a constant force of 215 N. The cart experiences a force due to gravity of 2 885 N. The rope between the cart and the mule makes an angle of 19ยฐ to the horizontal. The cart does not move.

Find the magnitude and direction of the frictional force preventing the cart from moving.

INSTRUCTION: Round your answer to two decimal places.
Answer:

Fโ†’friction= N

one-of
type(numeric.abserror(0.01))


ID is: 3791 Seed is: 2588

Normal force on a horizontal surface

An object is on a horizontal surface. Riaan pulls the object at an angle out of the surface with a force Fโ†’. The object remains in contact with the surface.

  1. How does the magnitude of the normal force (FN) compare to the magnitude of the gravitational force (Fg)?

    Answer:

    FN is Fg.

  2. The force Fโ†’ is applied at an angle ฮธ to the horizontal. Which one of the following is a correct expression for the magnitude of the normal force in this scenario?

    FN= ...

    A Fgโˆ’F
    B Fgโˆ’Fsinโก(ฮธ)
    C Fg+Fsinโก(ฮธ)
    D Fg+F
    E Fg
    Answer:

    The correct expression is: .


ID is: 3791 Seed is: 9533

Normal force on a horizontal surface

An object is on a horizontal surface. Heather pulls the object straight up with a force Fโ†’. The object remains in contact with the surface.

  1. How does the magnitude of the normal force (FN) compare to the magnitude of the gravitational force (Fg)?

    Answer:

    FN is Fg.

  2. Which one of the following is a correct expression for the magnitude of the normal force in this scenario?

    FN= ...

    A Fgโˆ’F
    B Fg
    C Fg+F
    D Fโˆ’Fg
    E F
    Answer:

    The correct expression is: .



ID is: 3772 Seed is: 2357

MCQ: Free-body diagrams

Bongani is travelling in a taxi along a straight horizontal road to the right.

The taxi is travelling at a constant speed of 80 kmยทhโˆ’1. Which one of the following free-body diagrams best represents all the forces acting on Bongani and the taxi?

A
B
C
D
Answer:

ID is: 3772 Seed is: 5105

MCQ: Free-body diagrams

Rebecca is driving a bus along a straight horizontal street to the left.

The bus is travelling at a constant speed of 40 kmยทhโˆ’1. Which one of the following free-body diagrams best represents all the forces acting on Rebecca and the bus?

A
B
C
D
Answer:


ID is: 3812 Seed is: 4171

Normal force on an inclined plane

A box is on an inclined plane which forms an angle ฮฑ with the horizontal. Heather pulls the box at an angle out of the slope with a force Fโ†’. The box remains in contact with the surface.

  1. How does the magnitude of the normal force (FN) compare to the magnitude of the perpendicular component of the gravitational force (Fg,โŠฅ)?
  2. The magnitudes of the normal force (FN) and the full gravitational force (Fg) have the following relationship:
    A FN=Fg
    B FN>Fg
    C FN<Fg
    D Impossible to determine.
Answer:
  1. FN is Fg,โŠฅ.
  2. When comparing FN to Fg, the correct relationship is .

ID is: 3812 Seed is: 7139

Normal force on an inclined plane

A crate is on an inclined plane which forms an angle ฮฑ with the horizontal. Amina pushes the crate perpendicularly into the slope with a force Fโ†’.

  1. How does the magnitude of the normal force (FN) compare to the magnitude of the perpendicular component of the gravitational force (Fg,โŠฅ)?
  2. The magnitudes of the normal force (FN) and the full gravitational force (Fg) have the following relationship:
    A FN=Fg
    B FN<Fg
    C FN>Fg
    D Impossible to determine.
Answer:
  1. FN is Fg,โŠฅ.
  2. When comparing FN to Fg, the correct relationship is .


ID is: 3855 Seed is: 5579

Match the free-body diagram to a scenario

The following free-body diagram (to scale) shows all the forces exerted on an object.

  1. Is the object in equilibrium? Give a reason for your answer.

    Answer:

    The object in equilibrium. We know this because the net force exerted on the object is .

  2. Which one of the following scenarios contains an object that could be described by the given free-body diagram?

    A Ndidi places a block in a lift which accelerates down.
    B Ndidi places a block in a lift which moves down at a constant velocity.
    C Ndidi exerts a pushing force to the left on a block on a rough horizontal surface, and the block slides across the surface at a constant velocity.
    D Ndidi exerts a pulling force to the left on a system of two blocks on a rough horizontal surface, but the system remains at rest.
    Answer:

    The correct scenario is:


ID is: 3855 Seed is: 1052

Match the free-body diagram to a scenario

The following free-body diagram (to scale) shows all the forces exerted on an object.

  1. Is the object in equilibrium? Give a reason for your answer.

    Answer:

    The object in equilibrium. We know this because the net force exerted on the object is .

  2. Which one of the following scenarios contains an object that could be described by the given free-body diagram?

    A Johan connects a box to a light inextensible rope which is run over a frictionless pulley. Johan pulls on the rope, but the box accelerates down.
    B Johan exerts a pulling force to the right on a box on a rough horizontal surface, and the box accelerates to the right.
    C Johan throws a ball upwards from the roof of a tall building. Once the ball leaves contact with Johan's hand it moves up, while being slowed down by the gravitational force only.
    D Johan connects a box to a light inextensible rope which is run over a frictionless pulley. Johan pulls on the rope, but the box hangs motionless.
    Answer:

    The correct scenario is:



ID is: 4533 Seed is: 1998

Closed and open vector diagrams

Adapted from DBE Nov 2016 Grade 11, P1, Q2
Physical constants ยท Physics formulas

A heavy object is being lifted upwards with a constant speed using two ropes and two pulleys, as shown in the diagram below. The two pulleys are a distance x apart. The force in Rope A (Fโ†’A) is 824,8 N and the force in Rope B (Fโ†’B) is 697,1 N. Rope A makes an angle of 65ยฐ with the horizontal and Rope B makes an angle of 30ยฐ with the vertical.

Will the vector diagram of Force Fโ†’A, Force Fโ†’B, and the weight of the object be closed or open? Give a reason for your answer.

Answer:

The vector diagram will be . This is because:


ID is: 4533 Seed is: 2329

Closed and open vector diagrams

Adapted from DBE Nov 2016 Grade 11, P1, Q2
Physical constants ยท Physics formulas

A heavy object is being lifted upwards with a constant speed using two ropes and two pulleys, as shown in the diagram below. The two pulleys are a distance x apart. The force in Rope A (Fโ†’A) is 710,6 N and the force in Rope B (Fโ†’B) is 1 038,9 N. Rope A makes an angle of 30ยฐ with the vertical and Rope B makes an angle of 70ยฐ with the horizontal.

Will the vector diagram of Force Fโ†’A, Force Fโ†’B, and the weight of the object be closed or open? Give a reason for your answer.

Answer:

The vector diagram will be . This is because:



ID is: 3794 Seed is: 148

Normal force on an inclined plane

A box is on an inclined plane which forms an angle ฮฑ with the horizontal. Rebecca pulls the box at an angle out of the slope with a force Fโ†’. The box remains in contact with the surface.

    1. How does the magnitude of the normal force (FN) compare to the magnitude of the perpendicular component of the gravitational force (Fg,โŠฅ)?
    2. The magnitudes of the normal force (FN) and the full gravitational force (Fg) have the following relationship:
      A FN<Fg
      B FN>Fg
      C FN=Fg
      D Impossible to determine.
    Answer:
    1. FN is Fg,โŠฅ.
    2. When comparing FN to Fg, the correct relationship is .
  1. The force Fโ†’ is applied at an angle ฮธ to the slope. Which one of the following is a correct expression for the magnitude of the normal force in this scenario?

    FN= ...

    A Fgโˆ’Fsinโก(ฮธ)
    B Fg
    C Fgcosโก(ฮฑ)+Fsinโก(ฮธ)
    D Fg+Fsinโก(ฮธ)
    E Fgcosโก(ฮฑ)โˆ’Fsinโก(ฮธ)
    F Fgcosโก(ฮฑ)
    Answer:

    The correct expression is: .


ID is: 3794 Seed is: 7671

Normal force on an inclined plane

A box is on an inclined plane which forms an angle ฮฑ with the horizontal. Christopher pushes the box at an angle into the slope with a force Fโ†’.

    1. How does the magnitude of the normal force (FN) compare to the magnitude of the perpendicular component of the gravitational force (Fg,โŠฅ)?
    2. The magnitudes of the normal force (FN) and the full gravitational force (Fg) have the following relationship:
      A FN<Fg
      B FN>Fg
      C FN=Fg
      D Impossible to determine.
    Answer:
    1. FN is Fg,โŠฅ.
    2. When comparing FN to Fg, the correct relationship is .
  1. The force Fโ†’ is applied at an angle ฮธ to the slope. Which one of the following is a correct expression for the magnitude of the normal force in this scenario?

    FN= ...

    A Fgcosโก(ฮฑ)โˆ’Fsinโก(ฮธ)
    B Fgโˆ’Fsinโก(ฮธ)
    C Fgcosโก(ฮฑ)+Fsinโก(ฮธ)
    D Fg+Fsinโก(ฮธ)
    E Fg
    F Fgcosโก(ฮฑ)
    Answer:

    The correct expression is: .



ID is: 1547 Seed is: 7994

Components of forces

A box that experiences a gravitational force of 911,4 N is placed on a slope that makes an angle of 40ยฐ with the horizontal. The box does not slide down the slope. Calculate the magnitude and direction of the frictional force and the normal force present in this situation.

INSTRUCTION: Round your answers to two decimal places.
Answer:

fโ†’s= N
Fโ†’N= N

one-of
type(numeric.abserror(0.01))
one-of
type(numeric.abserror(0.01))

ID is: 1547 Seed is: 3063

Components of forces

A suitcase that experiences a gravitational force of 548,8 N is placed on a slope that makes an angle of 47ยฐ with the horizontal. The suitcase does not slide down the slope. Calculate the magnitude and direction of the frictional force and the normal force present in this situation.

INSTRUCTION: Round your answers to two decimal places.
Answer:

fโ†’s= N
Fโ†’N= N

one-of
type(numeric.abserror(0.01))
one-of
type(numeric.abserror(0.01))


ID is: 4532 Seed is: 8298

Pulleys and vector components

Adapted from DBE Nov 2016 Grade 11, P1, Q2
Physical constants ยท Physics formulas

A heavy object is lifted using two ropes and two pulleys, as shown in the diagram below. The two pulleys are a distance x apart. The force in Rope A (Fโ†’A) is 676,7 N and the force in Rope B (Fโ†’B) is 800,6 N. Rope A makes an angle of 60ยฐ with the horizontal and Rope B makes an angle of 25ยฐ with the vertical.

  1. Calculate the magnitude of the:

    1. vertical component of Fโ†’B
    2. horizontal component of Fโ†’B
    INSTRUCTION: Round your answers to two decimal places.
    Answer:
    1. FB,y=
    2. FB,x=
    one-of
    type(numeric.abserror(0.01))
    one-of
    type(numeric.abserror(0.01))
  2. Calculate the maximum weight that the two forces can lift.

    INSTRUCTION: Round your answer to two decimal places.
    Answer:

    The maximum weight is .

    one-of
    type(numeric.abserror(0.01))

ID is: 4532 Seed is: 3494

Pulleys and vector components

Adapted from DBE Nov 2016 Grade 11, P1, Q2
Physical constants ยท Physics formulas

A heavy object is lifted using two ropes and two pulleys, as shown in the diagram below. The two pulleys are a distance x apart. The force in Rope A (Fโ†’A) is 884,6 N and the force in Rope B (Fโ†’B) is 470,7 N. Rope A makes an angle of 70ยฐ with the horizontal and Rope B makes an angle of 40ยฐ with the vertical.

  1. Calculate the magnitude of the:

    1. vertical component of Fโ†’A
    2. horizontal component of Fโ†’A
    INSTRUCTION: Round your answers to two decimal places.
    Answer:
    1. FA,y=
    2. FA,x=
    one-of
    type(numeric.abserror(0.01))
    one-of
    type(numeric.abserror(0.01))
  2. Calculate the maximum weight that the two forces can lift.

    INSTRUCTION: Round your answer to two decimal places.
    Answer:

    The maximum weight is .

    one-of
    type(numeric.abserror(0.01))


ID is: 3771 Seed is: 4058

MCQ: Unequal forces

An object moving with a uniform velocity on a horizontal surface has several unequal forces acting on it.

Which one of the following statements must be true?

A The net force must be zero.
B At least two of the forces must be acting in the same direction.
C At least two of the forces must be acting in opposite directions.
D The net force must be non-zero.
Answer:

ID is: 3771 Seed is: 2328

MCQ: Unequal forces

A body moving with a constant velocity on a horizontal surface has several unequal forces acting on it.

Which one of the following statements must be true?

A Friction balances out the forces acting in the direction of motion.
B At least two of the forces must be acting in opposite directions.
C The resultant of the forces must be zero.
D The resultant force must act against the direction of motion.
Answer:


ID is: 4534 Seed is: 9074

The distance between pulleys

Adapted from DBE Nov 2016 Grade 11, P1, Q2
Physical constants ยท Physics formulas

A heavy object is lifted upwards with a constant speed using two ropes and two pulleys, as shown in the diagram below. The two pulleys are a distance x apart. The force in Rope A (Fโ†’A) is 458,4 N and the force in Rope B (Fโ†’B) is 697,2 N. Rope A makes an angle of 40ยฐ with the vertical and Rope B makes an angle of 65ยฐ with the horizontal.

The distance x between the centres of the pulleys is decreased. Will the pulley system be more or less effective? Give a reason for your answer.

Answer:

The pulley system will be effective. This is because:


ID is: 4534 Seed is: 9529

The distance between pulleys

Adapted from DBE Nov 2016 Grade 11, P1, Q2
Physical constants ยท Physics formulas

A heavy object is accelerated upwards using two ropes and two pulleys, as shown in the diagram below. The two pulleys are a distance x apart. The force in Rope A (Fโ†’A) is 508,2 N and the force in Rope B (Fโ†’B) is 334,1 N. Rope A makes an angle of 25ยฐ with the vertical and Rope B makes an angle of 50ยฐ with the horizontal.

The distance x between the centres of the pulleys is decreased. Will the pulley system be more or less effective? Give a reason for your answer.

Answer:

The pulley system will be effective. This is because:



ID is: 4567 Seed is: 2384

Equilibrium on a rough horizontal surface

Adapted from DBE Nov 2015 Grade 11, P1, Q3
Physical constants ยท Physics formulas

A 25 kg block is placed on a rough horizontal surface. A constant force (Fโ†’) pulls the block, but the block remains at rest as shown in the diagram below. The coefficient of static friction (ฮผs) between the block and the surface is 0,67. If the magnitude of the applied force were any larger, the block would begin to move.

  1. Calculate the magnitudes of:

    1. Force Fโ†’.
    2. The normal force acting on the block.
    INSTRUCTION: Round your answers to two decimal places.
    Answer:
    1. F=
    2. FN=
    numeric
    numeric
  2. Calculate the magnitude of the maximum static frictional force.

    INSTRUCTION: Round your answer to two decimal places.
    Answer:

    fs,max=

    numeric

ID is: 4567 Seed is: 8861

Equilibrium on a rough horizontal surface

Adapted from DBE Nov 2015 Grade 11, P1, Q3
Physical constants ยท Physics formulas

A 40 kg block is placed on a rough horizontal surface. A constant force (Fโ†’) pulls the block and the block moves across the surface at a constant speed as shown in the diagram below. The coefficient of kinetic friction (ฮผk) between the block and the surface is 0,58.

  1. Calculate the magnitudes of:

    1. Force Fโ†’.
    2. The normal force acting on the block.
    INSTRUCTION: Round your answers to two decimal places.
    Answer:
    1. F=
    2. FN=
    numeric
    numeric
  2. Calculate the magnitude of the kinetic frictional force.

    INSTRUCTION: Round your answer to two decimal places.
    Answer:

    fk=

    numeric

10. Systems and pulleys



ID is: 3835 Seed is: 9311

Multiple choice: Feel the tension!

Adapted from DBE Feb-Mar 2017 Grade 12, P1, Q1.2
Physical constants ยท Physics formulas

The diagram below shows two blocks, P and Q, suspended from a ceiling. The blocks are stationary and have the same mass, but different heights above the ground.

The connecting strings are massless and inextensible. The tensions in the strings attached to blocks P and Q are TP and TQ respectively. In the diagram below, the size of the box represents its mass.

Which one of the following statements about how the tensions compare to each other is correct?

A TP>TQ
B TP<TQ
C TP=TQ
D impossible to determine
Answer:

ID is: 3835 Seed is: 464

Multiple choice: Feel the tension!

Adapted from DBE Feb-Mar 2017 Grade 12, P1, Q1.2
Physical constants ยท Physics formulas

The diagram below shows two blocks, R and S, suspended from a ceiling. The blocks are stationary and have different masses, but the same height above the ground.

The connecting strings are massless and inextensible. The tensions in the strings attached to blocks R and S are TR and TS respectively. In the diagram below, the size of the box represents its mass.

Which one of the following statements about how the tensions compare to each other is correct?

A TR>TS
B TR<TS
C TR=TS
D impossible to determine
Answer:


ID is: 1468 Seed is: 5602

Newton's second law

A 2 800 kg truck pulls a 1 030 kg trailer with a constant acceleration. The tow bar between the truck and trailer makes an angle 40ยฐ degrees with the horizontal. The engine of the truck produces a thrust of 8 000 N.

Calculate the magnitude of the tension T between the truck and the trailer, and the magnitude of the acceleration a of the truck. Ignore the effects of friction.

INSTRUCTION: Round your answers to two decimal places.
Answer:

T= N

a= mยทsโˆ’2

one-of
type(numeric.abserror(0.01))
one-of
type(numeric.abserror(0.01))

ID is: 1468 Seed is: 9429

Newton's second law

A 1 900 kg bus pulls a 1 210 kg trailer with a constant acceleration. The tow bar between the bus and trailer makes an angle 45ยฐ degrees with the horizontal. The engine of the bus produces a thrust of 10 000 N.

Calculate the magnitude of the tension T between the bus and the trailer, and the magnitude of the acceleration a of the bus. Ignore the effects of friction.

INSTRUCTION: Round your answers to two decimal places.
Answer:

T= N

a= mยทsโˆ’2

one-of
type(numeric.abserror(0.01))
one-of
type(numeric.abserror(0.01))


ID is: 1554 Seed is: 4569

A system accelerating horizontally on a rough surface

Two crates, with masses 20 kg and 10 kg respectively, are connected with a thick rope as shown in the diagram below. A force of 600 N is applied towards the right on the 10 kg crate. The crates experience an acceleration of 3 mยทsโˆ’2 to the right.

The crates are made of the same material and so they experience the same coefficient of kinetic friction with the surface.

TIP: The frictional force experienced by each crate will be proportional to its mass. This is because the crates have the same coefficient of kinetic friction (ฮผk).
  1. Calculate the magnitude and direction of the frictional force acting on the 10 kg crate (the crate on the right).

    INSTRUCTION: Round your answer to two decimal places.
    Answer:

    fโ†’k,2= N

    one-of
    type(numeric.abserror(0.01))
  2. Calculate the magnitude of the tension T in the rope.

    INSTRUCTION: Round your answer to two decimal places.
    Answer:

    T= N

    one-of
    type(numeric.abserror(0.01))

ID is: 1554 Seed is: 2406

A system accelerating horizontally on a rough surface

Two crates, with masses 20 kg and 15 kg respectively, are connected with a thick rope as shown in the diagram below. A force of 800 N is applied towards the right on the 15 kg crate. The crates experience an acceleration of 4 mยทsโˆ’2 to the right.

The crates are made of the same material and so they experience the same coefficient of kinetic friction with the surface.

TIP: The frictional force experienced by each crate will be proportional to its mass. This is because the crates have the same coefficient of kinetic friction (ฮผk).
  1. Calculate the magnitude and direction of the frictional force acting on the 15 kg crate (the crate on the right).

    INSTRUCTION: Round your answer to two decimal places.
    Answer:

    fโ†’k,2= N

    one-of
    type(numeric.abserror(0.01))
  2. Calculate the magnitude of the tension T in the rope.

    INSTRUCTION: Round your answer to two decimal places.
    Answer:

    T= N

    one-of
    type(numeric.abserror(0.01))


ID is: 3669 Seed is: 9304

Systems on rough inclined slopes

A box of mass 10 kg is connected to another box of mass 3 kg by a light inextensible rope. The system is pulled up a rough slope inclined at 50ยฐ to the vertical, by means of a constant 110 N force parallel to the slope as shown in the diagram below.

The boxes are not made from the same material. The magnitude of the kinetic frictional force between the surface and the 3 kg box is 10,81 N. The coefficient of kinetic friction between the 10 kg box and the surface is 0,48.

  1. Calculate the magnitude of the kinetic frictional force between the 10 kg box and the surface of the slope.

    INSTRUCTION:
    • Round your answer to two decimal places.
    • Use the values given here for any physical constants that you may need.
    Answer:

    fk,1=

    one-of
    type(numeric.abserror(0.01))
  2. Calculate the magnitude of the tension in the rope connecting the two boxes.

    INSTRUCTION:
    • Round your answer to two decimal places.
    • Use the values given here for any physical constants that you may need.
    Answer:

    T=

    one-of
    type(numeric.abserror(0.01))

ID is: 3669 Seed is: 2236

Systems on rough inclined slopes

A block of mass 3 kg is connected to another block of mass 2 kg by a light inextensible string. The system is pulled up a rough slope inclined at 31ยฐ to the horizontal, by means of a constant 40 N force parallel to the slope as shown in the diagram below.

The blocks are not made from the same material. The magnitude of the kinetic frictional force between the surface and the 2 kg block is 9,07 N. The coefficient of kinetic friction between the 3 kg block and the surface is 0,54.

  1. Calculate the magnitude of the kinetic frictional force between the 3 kg block and the surface of the slope.

    INSTRUCTION:
    • Round your answer to two decimal places.
    • Use the values given here for any physical constants that you may need.
    Answer:

    fk,1=

    one-of
    type(numeric.abserror(0.01))
  2. Calculate the magnitude of the tension in the string connecting the two blocks.

    INSTRUCTION:
    • Round your answer to two decimal places.
    • Use the values given here for any physical constants that you may need.
    Answer:

    T=

    one-of
    type(numeric.abserror(0.01))


ID is: 3614 Seed is: 7609

Hanging blocks

A block of mass 8,9 kg is connected to another block of mass 4,2 kg by a light inextensible cable. This system of blocks is then suspended from the ceiling by the top block, using the same type of cable.

  1. The hanging system of blocks is in static equilibrium. What does this mean?

    A The system is stationary because it experiences the static frictional force.
    B The top block and the bottom block must have the same mass in order to be balanced.
    C The acceleration and velocity of the system are both zero.
    D The system only experiences electrostatic forces.
    Answer:

    The correct statement is:

  2. Draw labelled free-body diagrams indicating all the forces acting on each block.

    Now compare your diagrams to the two diagrams given below and answer the questions that follow.

    Diagram A

    Diagram B

    1. Which diagram is the free-body diagram for the bottom block?
    2. Which force does Force Xโ†’ represent?
    Answer:
    1. Diagram is the free-body diagram for the bottom block.
    2. Force Xโ†’ represents the force acting on the block.
  3. Calculate the magnitude of the tensional force in the bottom cable (T2).

    INSTRUCTIONS:
    • Round your answer to one decimal place.
    • Use the values given here for any physical constants that you may need.
    Answer:

    T2=

    one-of
    type(numeric.abserror(0.1))
  4. Calculate the magnitude of the tensional force in the top cable (T1).

    INSTRUCTIONS:
    • Where appropriate, use unrounded answers from the previous question.
    • Round your answer to the nearest integer.
    • Use the values given here for any physical constants that you may need.
    Answer:

    T1=

    numeric

ID is: 3614 Seed is: 1687

Hanging blocks

A block of mass 7,8 kg is connected to another block of mass 5,8 kg by a light inextensible rope. This system of blocks is then suspended from the ceiling by the top block, using the same type of rope.

  1. The hanging system of blocks is in static equilibrium. What does this mean?

    A The system gently swings from side to side.
    B The Newton's third law action-reaction pairs all cancel each other out.
    C The acceleration and velocity of the system are both zero.
    D The system is stationary because it experiences the static frictional force.
    Answer:

    The correct statement is:

  2. Draw labelled free-body diagrams indicating all the forces acting on each block.

    Now compare your diagrams to the two diagrams given below and answer the questions that follow.

    Diagram A

    Diagram B

    1. Which diagram is the free-body diagram for the bottom block?
    2. Which force does Force Pโ†’ represent?
    Answer:
    1. Diagram is the free-body diagram for the bottom block.
    2. Force Pโ†’ represents the force acting on the block.
  3. Calculate the magnitude of the tensional force in the bottom rope (T2).

    INSTRUCTIONS:
    • Round your answer to one decimal place.
    • Use the values given here for any physical constants that you may need.
    Answer:

    T2=

    one-of
    type(numeric.abserror(0.1))
  4. Calculate the magnitude of the tensional force in the top rope (T1).

    INSTRUCTIONS:
    • Where appropriate, use unrounded answers from the previous question.
    • Round your answer to the nearest integer.
    • Use the values given here for any physical constants that you may need.
    Answer:

    T1=

    numeric


ID is: 3238 Seed is: 2348

Tension and pulleys

Two blocks of masses 40 kg and 10 kg are connected by a light inextensible string, U. A second light inextensible string, V, attached to the 10 kg block, runs over a massless frictionless pulley. A constant horizontal force of 350 N pulls string V as shown in the diagram below. The magnitudes of the tensions in U and V are T1 and T2 respectively. Ignore the effects of air friction.

  1. Which one of following diagrams is a correctly labelled free-body diagram showing all the forces acting on the the 40 kg block?

    A
    B
    C
    D
    Answer:

    The correct diagram is:

  2. Calculate the magnitude of the tension T1 in String U as well as the acceleration of the 40 kg block.

    INSTRUCTIONS:
    • Round both of your final answers to two decimal places.
    • You must use these values for any physical constants that you might need.
    Answer:

    T1=
    aโ†’=

    one-of
    type(numeric.abserror(0.01))
    one-of
    type(numeric.abserror(0.01))
  3. When the 350 N force is replaced by a sharp pull on the string, one of the two strings will break.

    Which one of the two strings, U or V, will break?

    Answer:

    String will break.


ID is: 3238 Seed is: 5074

Tension and pulleys

Two blocks of masses 35 kg and 20 kg are connected by a light inextensible string, W. A second light inextensible string, X, attached to the 20 kg block, runs over a massless frictionless pulley. A constant horizontal force of 450 N pulls the second string as shown in the diagram below. The magnitudes of the tensions in W and X are T1 and T2 respectively. Ignore the effects of air friction.

  1. Which one of following diagrams is a correctly labelled free-body diagram representing all the forces acting on the the 20 kg block?

    A
    B
    C
    D
    Answer:

    The correct diagram is:

  2. Calculate the magnitude of the tension T1 in String W as well as the acceleration of the 20 kg block.

    INSTRUCTIONS:
    • Round both of your final answers to two decimal places.
    • You must use these values for any physical constants that you might need.
    Answer:

    T1=
    aโ†’=

    one-of
    type(numeric.abserror(0.01))
    one-of
    type(numeric.abserror(0.01))
  3. When the 450 N force is replaced by a sharp tug on the string, one of the two strings will break.

    Which one of the two strings, W or X, will break?

    Answer:

    String will break.



ID is: 3678 Seed is: 1627

Dog sledding

A team of dogs pulls two dog sleds across a frozen pond. The sled at the front has an unknown mass m2 and the sled at the back has a mass of 140 kg. The ropes attached to the dogs form an angle of 9ยฐ with the horizontal and the dogs pull with a constant force of 280 N.

While the sleds are being pulled, the front sled experiences a normal force of 570 N and the tension in the horizontal rope connecting the two sleds is T. All forms of friction can be ignored.

NOTE:

A sled is used for transport. It either has a flat bottom or long, thin strips of metal or wood attached to the bottom. A dog sled is pulled by one or more dogs (often huskies) and is used to move over ice and through snow. There are many different types of dog sled, with some being used for transport and others being used for racing.

  1. Draw labelled free-body diagrams showing all the forces acting on both of the sleds as they are pulled by the dogs. Compare your diagrams to the two diagrams given below.

    For each of the forces labelled X, Y, and Z indicate:

    • the type of force represented.
    • which sled experiences the force.
    Answer:

    X is the force on the sled

    Y is the force on the sled

    Z is the force on the sled

  2. Calculate the mass of the front sled, m2.

    INSTRUCTIONS:
    • Round your answer to one decimal place.
    • Use the values given here for any physical constants that you may need.
    Answer:

    m2=

    one-of
    type(numeric.abserror(0.1))
  3. Calculate the acceleration of the sleds as well as the tension in the rope connecting the two sleds.

    INSTRUCTION:
    • Round both of your final answers to two decimal places.
    • Where appropriate, use unrounded answers from previous calculations.
    • Use the values given here for any physical constants that you may need.
    Answer:

    aโ†’=

    T=

    one-of
    type(numeric.abserror(0.01))
    one-of
    type(numeric.abserror(0.01))

ID is: 3678 Seed is: 3575

Dog sledding

A team of dogs pulls two dog sleds across a frozen pond. The sled at the front has an unknown mass m2 and the sled at the back has a mass of 150 kg. The ropes attached to the dogs form an angle of 8ยฐ with the horizontal and the dogs pull with a constant force of 350 N.

While the sleds are being pulled, the front sled experiences a normal force of 800 N and the tension in the horizontal rope connecting the two sleds is T. All forms of friction can be ignored.

NOTE:

A sled is used for transport. It either has a flat bottom or long, thin strips of metal or wood attached to the bottom. A dog sled is pulled by one or more dogs (often huskies) and is used to move over ice and through snow. There are many different types of dog sled, with some being used for transport and others being used for racing.

  1. Draw labelled free-body diagrams indicating all the forces acting on both of the sleds as they are pulled by the dogs. Compare your diagrams to the two diagrams given below.

    For each of the forces labelled X, Y, and Z indicate:

    • the type of force represented.
    • which sled experiences the force.
    Answer:

    X is the force on the sled

    Y is the force on the sled

    Z is the force on the sled

  2. Calculate the mass of the front sled, m2.

    INSTRUCTIONS:
    • Round your answer to one decimal place.
    • Use the values given here for any physical constants that you may need.
    Answer:

    m2=

    one-of
    type(numeric.abserror(0.1))
  3. Calculate the acceleration of the sleds as well as the tension in the rope connecting the two sleds.

    INSTRUCTION:
    • Round both of your final answers to two decimal places.
    • Where appropriate, use unrounded answers from previous calculations.
    • Use the values given here for any physical constants that you may need.
    Answer:

    aโ†’=

    T=

    one-of
    type(numeric.abserror(0.01))
    one-of
    type(numeric.abserror(0.01))


ID is: 3613 Seed is: 4249

Hanging blocks

A block of mass 6,9 kg is connected to another block of mass 5,7 kg by a light inextensible cable. This system of blocks is then suspended from the ceiling by the top block, using the same type of cable.

  1. Calculate the magnitude of the tensional force in each string.

    INSTRUCTIONS:
    • Do not round any values from intermediate steps.
    • Round both of your final answers to one decimal place.
    • You must use these values for any physical constants that you might need.
    Answer:

    T1=

    T2=

    one-of
    type(numeric.abserror(0.1))
    one-of
    type(numeric.abserror(0.1))
  2. Imagine that the entire system is moved to Pluto (a dwarf planet) which has a gravitational acceleration of 5,95ร—10โˆ’7 mยทsโˆ’2.

    What effect will this have on:

    1. the mass of the top block?
    2. the tension in the cable connecting the top block to the ceiling ?
    Answer:
    1. The mass of the top block will .
    2. The tension in the cable connecting the top block to the ceiling will .

ID is: 3613 Seed is: 8105

Hanging blocks

A block of mass 8,4 kg is connected to another block of mass 9,1 kg by a light inextensible string. This system of blocks is then suspended from the ceiling by the top block, using the same type of string.

  1. Calculate the magnitude of the tensional force in each string.

    INSTRUCTIONS:
    • Do not round any values from intermediate steps.
    • Round both of your final answers to one decimal place.
    • You must use these values for any physical constants that you might need.
    Answer:

    T1=

    T2=

    one-of
    type(numeric.abserror(0.1))
    one-of
    type(numeric.abserror(0.1))
  2. Imagine that the entire system is moved to Triton (a moon of Neptune) which has a gravitational acceleration of 7,83ร—10โˆ’7 mยทsโˆ’2.

    What effect will this have on:

    1. the mass of the bottom block?
    2. the tension in the string connecting the two blocks ?
    Answer:
    1. The mass of the bottom block will .
    2. The tension in the string connecting the two blocks will .


ID is: 4016 Seed is: 4494

A pulley and a smooth slope

Adapted from WCED Metro Central Sep 2017 Grade 12, P1, Q2.1
Physical constants ยท Physics formulas

Two heavy wooden crates of mass 20 kg and 10 kg respectively are placed on a smooth slope inclined at an angle of 10ยฐ to the horizontal. The crates are connected to each other by a light inextensible cable. The same type of cable is connected to the top crate, and the cable is run over a massless and frictionless pulley at the top of the slope and connected to a motor. Refer to the diagram below (not to scale).

The motor pulls on the top crate with a force of 80 N, via the cable. The force exerted by the motor is such that the system of crates accelerates up the slope with acceleration aโ†’. Ignore all forms of friction between the crates and the slope.

  1. Draw a free-body diagram showing all forces acting on the 10 kg crate (the top crate). Then use your free-body diagram to answer the following questions about the 10 kg crate.

    1. How many forces are in the free-body diagram?
    2. In which direction does the tensional force act?
    3. Does the motor exert a force on this crate?
    Answer:

    For the top crate:

    1. There is/are force(s) in the free-body diagram.
    2. The tensional force acts .
    3. The motor exert a force on this crate.
    numeric
  2. Calculate the:

    1. acceleration of the system of crates.
    2. magnitude of the tensional force in the cable between the crates.
    Answer:
    1. aโ†’=
    2. T=
    one-of
    type(numeric.abserror(0.01))
    one-of
    type(numeric.abserror(0.01))

ID is: 4016 Seed is: 5899

A pulley and a smooth slope

Adapted from WCED Metro Central Sep 2017 Grade 12, P1, Q2.1
Physical constants ยท Physics formulas

Two heavy wooden crates of mass 26 kg and 13 kg respectively are placed on a smooth slope inclined at an angle of 23ยฐ to the horizontal. The crates are connected to each other by a light inextensible cable. The same type of cable is connected to the top crate, and the cable is run over a massless and frictionless pulley at the top of the slope and connected to a motor. Refer to the diagram below (not to scale).

The motor pulls on the top crate with a force of 200 N, via the cable. The force exerted by the motor is such that the system of crates accelerates up the slope with acceleration aโ†’. Ignore all forms of friction between the crates and the slope.

  1. Draw a free-body diagram showing all forces acting on the 26 kg crate (the bottom crate). Then use your free-body diagram to answer the following questions about the 26 kg crate.

    1. How many forces are parallel to the slope, or have a component parallel to the slope?
    2. In which direction does the tensional force act?
    3. Does the motor exert a force on this crate?
    Answer:

    For the bottom crate:

    1. There is/are force(s) parallel to the slope, or that have a parallel component.
    2. The tensional force acts .
    3. The motor exert a force on this crate.
    numeric
  2. Calculate the:

    1. acceleration of the system of crates.
    2. magnitude of the tensional force in the cable between the crates.
    Answer:
    1. aโ†’=
    2. T=
    one-of
    type(numeric.abserror(0.01))
    one-of
    type(numeric.abserror(0.01))


ID is: 3449 Seed is: 5816

Pulley and a rough horizontal surface

A block of mass m1= 9,6 kg is attached to a block of mass m2 via a massless inextensible string which is passed over a frictionless pulley as shown in the diagram below. The block of mass m2 is at rest on a horizontal surface and the block of mass 9,6 kg hangs vertically over the pulley. The coefficient of static friction between the block and the surface is 0,49 and tension in the string is T. The suspended mass is at its largest possible value for the system to only just remain in static equilibrium.

  1. Which one of the following is a correctly labelled force diagram showing all the forces acting on the suspended block?

    A

    B

    C

    D

    Answer:

    The correct diagram is:

  2. Determine the magnitude of the tension in the string as well as the mass of the block on the horizontal surface.

    INSTRUCTIONS:
    • Round both of your final answers to two decimal places.
    • You must use these values for any physical constants that you might need.
    Answer:

    T=

    m2=

    one-of
    type(numeric.abserror(0.01))
    one-of
    type(numeric.abserror(0.01))
  3. Describe what will happen to the block on the horizontal surface if mass m2 (the block on the horizontal surface) is decreased.

    Describe what will happen to the block on the horizontal surface if mass m2 is increased.

    Answer:

    If m2 is decreased, the block on the horizontal surface will .

    If m2 is increased, the block on the horizontal surface will .


ID is: 3449 Seed is: 6581

Pulley and a rough horizontal surface

A block of mass m1 is attached to a block of mass m2= 19,5 kg via a light inextensible string which is passed over a frictionless pulley as shown in the diagram below. The block of mass 19,5 kg is at rest on a horizontal surface and the block of mass m1 hangs vertically over the pulley. The coefficient of static friction between the block and the surface is ฮผs and tension in the string is 100 N. The suspended mass is at its largest possible value for the system to only just remain in static equilibrium.

  1. Which one of the following is a correctly labelled force diagram representing all the forces acting on the suspended block?

    A

    B

    C

    D

    Answer:

    The correct diagram is:

  2. Determine the mass of the suspended block as well as the coefficient of static friction between the block and the rough surface.

    INSTRUCTIONS:
    • Round both of your final answers to two decimal places.
    • You must use these values for any physical constants that you might need.
    Answer:

    m1=

    ฮผs=

    one-of
    type(numeric.abserror(0.01))
    one-of
    type(numeric.abserror(0.01))
  3. Describe what will happen to the block on the horizontal surface if mass m1 (the suspended block) is increased.

    Describe what will happen to the block on the horizontal surface if mass m1 is decreased.

    Answer:

    If m1 is increased, the block on the horizontal surface will .

    If m1 is decreased, the block on the horizontal surface will .



ID is: 3548 Seed is: 5772

Pulley and a frictionless horizontal surface

Two blocks of different mass are attached to each other via a light inextensible string which is placed over a massless and frictionless pulley. Block 1 (mass 7 kg) is placed on a smooth surface and attached to the wall by a second string which makes an angle of 43ยฐ to the horizontal as shown in the diagram below. Block 2 (mass 7 kg) is left to hang freely. The entire system is in static equilibrium and all forms of friction can be ignored.

  1. Which one of the following is a correctly labelled force diagram showing all the forces acting on Block 1? The diagrams are all to scale.

    TIP: First draw the force diagram for Block 1 and then compare it to the options below.
    A
    B
    C
    D
    Answer:

    The correct diagram is:

  2. Determine the magnitude of the normal force exerted on Block 1.

    INSTRUCTIONS:
    • Round your final answer to two decimal places.
    • You must use these values for any physical constants that you might need.
    Answer:

    FN,1=

    one-of
    type(numeric.abserror(0.01))

ID is: 3548 Seed is: 284

Pulley and a frictionless horizontal surface

Two blocks of different mass are attached to each other via a light inextensible string which is placed over a massless and frictionless pulley. Block 1 (mass 7 kg) is placed on a smooth surface and attached to the wall by a second string which makes an angle of 53ยฐ to the horizontal as shown in the diagram below. Block 2 (mass 2 kg) is left to hang freely. The entire system is in static equilibrium and all forms of friction can be ignored.

  1. Which one of the following is a correctly labelled free-body diagram indicating all the forces acting on Block 1? The diagrams are all to scale.

    TIP: First draw the free-body diagram for Block 1 and then compare it to the options below.
    A
    B
    C
    D
    Answer:

    The correct diagram is:

  2. Determine the magnitude of the normal force exerted on Block 1.

    INSTRUCTIONS:
    • Round your final answer to two decimal places.
    • You must use these values for any physical constants that you might need.
    Answer:

    FN,1=

    one-of
    type(numeric.abserror(0.01))


ID is: 3672 Seed is: 2809

Systems on smooth inclined planes

A box of mass 8,7 kg is connected to another box of mass 2,5 kg by a light inextensible cable. The same type of cable is attached to the 2,5 kg box, run over a light frictionless pulley, and connected to a motor.

The motor pulls the system up a smooth plane inclined at an angle ฮฑ to the horizontal. The motor applies a constant force of 90 N which causes the system to accelerate at 0,59 mยทsโˆ’2. The force applied by the motor is parallel to the plane as shown in the diagram below. Ignore all forms of friction.

  1. Draw a labelled free-body diagram indicating all the forces acting on the 2,5 kg box.

    How many forces should there be in this diagram?Remember that a free-body diagram should contain actual forces, not components of forces.

    Answer:

    There is/are force(s) in the free-body diagram for the 2,5 kg box.

    one-of
    type(string)
  2. Here is the diagram again:

    Which one of the following expressions is equal to the magnitude of the net force experienced by the 2,5 kg box?

    TIP: Note that the angle is given to the horizontal!
    Answer:
  3. Here is the diagram again:

    Calculate the tension (T) in the cable connecting the two boxes as well as the angle (ฮฑ).

    INSTRUCTIONS:
    • Do not round any values from intermediate steps.
    • Round both of your final answers to two decimal places.
    • Use the values given here for any physical constants that you may need.
    Answer:

    T=

    ฮฑ = ยฐ

    one-of
    type(numeric.abserror(0.01))
    one-of
    type(numeric.abserror(0.01))

ID is: 3672 Seed is: 158

Systems on smooth inclined planes

A crate of mass 2,9 kg is connected to another crate of mass 6,5 kg by a light inextensible cable. The same type of cable is attached to the 6,5 kg crate, run over a light frictionless pulley, and connected to a motor.

The motor pulls the system up a smooth plane inclined at an angle ฮฑ to the vertical. The motor applies a constant force of 80 N which causes the system to accelerate at 0,39 mยทsโˆ’2. The force applied by the motor is parallel to the plane as shown in the diagram below. Ignore all forms of friction.

  1. Draw a labelled free-body diagram showing all the forces acting on the 6,5 kg crate.

    How many forces should there be in this diagram?Remember that a free-body diagram should contain actual forces, not components of forces.

    Answer:

    There is/are force(s) in the free-body diagram for the 6,5 kg crate.

    one-of
    type(string)
  2. Here is the diagram again:

    Which one of the following expressions is equal to the magnitude of the net force experienced by the 6,5 kg crate?

    TIP: Note that the angle is given to the vertical!
    Answer:
  3. Here is the diagram again:

    Calculate the tension (T) in the cable connecting the two crates as well as the angle (ฮฑ).

    INSTRUCTIONS:
    • Do not round any values from intermediate steps.
    • Round both of your final answers to two decimal places.
    • Use the values given here for any physical constants that you may need.
    Answer:

    T=

    ฮฑ = ยฐ

    one-of
    type(numeric.abserror(0.01))
    one-of
    type(numeric.abserror(0.01))


ID is: 3673 Seed is: 9347

Motoring up the ramp

A crate of mass 8,5 kg is connected to another crate of mass 2,1 kg by a light inextensible string. The same type of string is attached to the 2,1 kg crate, run over a light frictionless pulley, and connected to a motor.

The motor pulls the system up a smooth ramp inclined at an angle ฮฑ to the vertical. The motor applies a constant force of 90 N which causes the system to accelerate at 0,24 mยทsโˆ’2. The force applied by the motor is parallel to the ramp as shown in the diagram below. Ignore all forms of friction.

  1. Calculate the tension (T) in the string connecting the two crates as well as the angle (ฮฑ).

    INSTRUCTION:
    • Do not round any values from intermediate steps.
    • Round both of your final answers to two decimal places.
    • Use the values given here for any physical constants that you may need.
    Answer:

    T=

    ฮฑ = ยฐ

    one-of
    type(numeric.abserror(0.01))
    one-of
    type(numeric.abserror(0.01))
  2. The string connecting the top crate to the motor suddenly snaps (breaks).

    What effect will this have on:

    1. the tension in the string connecting the two crates?
    2. direction of acceleration of the crates?
    3. the magnitude of the acceleration of the crates?
    Answer:
    1. The magnitude of the tension in the string connecting the two crates will .
    2. The crates will accelerate the ramp.
    3. The magnitude of the acceleration will .

ID is: 3673 Seed is: 8681

Motoring up the ramp

A box of mass 7,4 kg is connected to another box of mass 2,8 kg by a light inextensible cable. The same type of cable is attached to the 2,8 kg box, run over a light frictionless pulley, and connected to a motor.

The motor pulls the system up a smooth ramp inclined at an angle ฮฑ to the vertical. The motor applies a constant force of 100 N which causes the system to accelerate at 1,92 mยทsโˆ’2. The force applied by the motor is parallel to the ramp as shown in the diagram below. Ignore all forms of friction.

  1. Calculate the tension (T) in the cable connecting the two boxes as well as the angle (ฮฑ).

    INSTRUCTION:
    • Do not round any values from intermediate steps.
    • Round both of your final answers to two decimal places.
    • Use the values given here for any physical constants that you may need.
    Answer:

    T=

    ฮฑ = ยฐ

    one-of
    type(numeric.abserror(0.01))
    one-of
    type(numeric.abserror(0.01))
  2. The cable connecting the top box to the motor suddenly snaps (breaks).

    What effect will this have on:

    1. the tension in the cable connecting the two boxes?
    2. direction of acceleration of the boxes?
    3. the magnitude of the acceleration of the boxes?
    Answer:
    1. The magnitude of the tension in the cable connecting the two boxes will .
    2. The boxes will accelerate the ramp.
    3. The magnitude of the acceleration will .


ID is: 4017 Seed is: 8724

Maximum static friction on a rough slope

Adapted from WCED Metro Central Sep 2017 Grade 12, P1, Q2.2
Physical constants ยท Physics formulas

A heavy wooden crate is placed on a rough slope inclined at an angle to the horizontal. A light inextensible cable is connected to the crate and the cable is run over a massless and frictionless pulley situated at the top of the slope and connected to a motor. The motor pulls on the crate with a force Fโ†’, via the cable. Refer to the diagram below (not to scale).

The value of the maximum static frictional force between the crate and slope is 64 N. The magnitude of the parallel component of the gravitational force acting on the crate is 75 N.

  1. Define the term maximum static frictional force in words.

    Answer:

    The maximum static frictional force (fโ†’s max) is the force that the relative motion between a object and a surface.

  2. For what range of values of the magnitude of the force applied by the motor (F) will the crate be in static equilibrium?

    Answer:

ID is: 4017 Seed is: 9132

Maximum static friction on a rough slope

Adapted from WCED Metro Central Sep 2017 Grade 12, P1, Q2.2
Physical constants ยท Physics formulas

A heavy wooden crate is placed on a rough slope inclined at an angle to the horizontal. A light inextensible cable is connected to the crate and the cable is run over a massless and frictionless pulley situated at the top of the slope and connected to a motor. The motor pulls on the crate with a force Fโ†’, via the cable. Refer to the diagram below (not to scale).

The value of the maximum static frictional force between the crate and slope is 73 N. The magnitude of the parallel component of the gravitational force acting on the crate is 84 N.

  1. Define the term maximum static frictional force in words.

    Answer:

    The maximum static frictional force (fโ†’s max) is the force that the relative motion between a object and a surface.

  2. For what range of values of the magnitude of the force applied by the motor (F) will the crate be in static equilibrium?

    Answer:


ID is: 3668 Seed is: 1345

Systems on rough inclined planes

A crate of mass 8 kg is connected to another crate of mass 7 kg by a light inextensible rope. The system is pulled up a rough plane inclined at 36ยฐ to the horizontal, by means of a constant 130 N force parallel to the plane as shown in the diagram below.

The crates are not made from the same material. The magnitude of the kinetic frictional force between the surface and the 7 kg crate is 23,31 N. The coefficient of kinetic friction between the 8 kg crate and the surface is 0,42.

  1. Draw a labelled free-body diagram showing all the forces acting on the 8 kg crate as it moves up the plane.

    Compare your diagram to the diagram given below. Is the given diagram correct? Choose a reason for your answer from the options provided.

    1 there is a kinetic frictional force in the diagram
    2 there is a tensional force in the diagram
    3 the normal force in the diagram points up
    4 all forces are included and point in the correct direction
    Answer:

    The given diagram . This is because .

  2. Calculate the magnitude of the:

    1. Kinetic frictional force between the 8 kg crate and the surface of the plane.
    2. Tension in the rope connecting the two crates.
    INSTRUCTIONS:
    • Round both of your final answers to two decimal places.
    • Use the values given here for any physical constants that you may need.
    Answer:

    fk,1=

    T=

    one-of
    type(numeric.abserror(0.01))
    one-of
    type(numeric.abserror(0.01))

ID is: 3668 Seed is: 6228

Systems on rough inclined planes

A crate of mass 8 kg is connected to another crate of mass 2 kg by a light inextensible string. The system is pulled up a rough plane inclined at 37ยฐ to the vertical, by means of a constant 100 N force parallel to the plane as shown in the diagram below.

The crates are not made from the same material. The magnitude of the kinetic frictional force between the surface and the 2 kg crate is 4,95 N. The coefficient of kinetic friction between the 8 kg crate and the surface is 0,42.

  1. Draw a labelled free-body diagram showing all the forces acting on the 8 kg crate as it moves up the plane.

    Compare your diagram to the diagram given below. Is the given diagram correct? Choose a reason for your answer from the options provided.

    1 the normal force in the diagram points perpendicularly out of the plane
    2 all forces are included and point in the correct direction
    3 the gravitational force in the diagram points down
    4 there is a tensional force in the diagram
    Answer:

    The given diagram . This is because .

  2. Calculate the magnitude of the:

    1. Kinetic frictional force between the 8 kg crate and the surface of the plane.
    2. Tension in the string connecting the two crates.
    INSTRUCTIONS:
    • Round both of your final answers to two decimal places.
    • Use the values given here for any physical constants that you may need.
    Answer:

    fk,1=

    T=

    one-of
    type(numeric.abserror(0.01))
    one-of
    type(numeric.abserror(0.01))


ID is: 3215 Seed is: 114

Two pulleys with a box on a frictionless surface

A box of mass 17,0 kg is on a smooth horizontal surface. Two mass pieces of masses 3,0 kg and 1,6 kg are attached to the box via two light inextensible strings which are passed over massless and frictionless pulleys as shown in the diagram below.

Determine the acceleration of Mass 1 as well as the magnitudes of the tension in each string.

INSTRUCTION:
  • Round all of your answers to two decimal places.
  • You must use these values for any physical constants that you might need.
Answer:

aโ†’= mยทsโˆ’2
T1= N
T2= N

one-of
type(numeric.abserror(0.01))
one-of
type(numeric.abserror(0.01))
one-of
type(numeric.abserror(0.01))

ID is: 3215 Seed is: 5291

Two pulleys with a crate on a frictionless surface

A crate of mass 17,7 kg is on a smooth horizontal table. Two mass pieces of masses 2,9 kg and 2,2 kg are attached to the crate via two light inextensible strings which are passed over massless and frictionless pulleys as shown in the diagram below.

Determine the acceleration of Mass 2 as well as the magnitudes of the tension in each string.

INSTRUCTION:
  • Round all of your answers to two decimal places.
  • You must use these values for any physical constants that you might need.
Answer:

aโ†’= mยทsโˆ’2
T1= N
T2= N

one-of
type(numeric.abserror(0.01))
one-of
type(numeric.abserror(0.01))
one-of
type(numeric.abserror(0.01))


ID is: 3679 Seed is: 4744

Physics is going to the dogs!

A team of dogs pulls two dog sleds across a frozen pond. The sled at the front has an unknown mass m2 and the sled at the back has a mass of 150 kg. The ropes attached to the dogs form an angle of 16ยฐ with the horizontal and the dogs pull with a constant force of 250 N.

While the sleds are being pulled, the front sled experiences a normal force of 560 N and the tension in the horizontal rope connecting the two sleds is T. All forms of friction can be ignored.

NOTE:

A sled is used for transport. It either has a flat bottom or long, thin strips of metal or wood attached to the bottom. A dog sled is pulled by one or more dogs (often huskies) and is used to move over ice and through snow. There are many different types of dog sled, with some being used for transport and others being used for racing.

  1. Calculate the acceleration of the sleds as well as the tension in the rope connecting the two sleds.

    INSTRUCTION:
    • Round both of your final answers to two decimal places.
    • Where appropriate, use unrounded answers from previous calculations.
    • Use the values given here for any physical constants that you may need.
    Answer:

    aโ†’=

    T=

    one-of
    type(numeric.abserror(0.01))
    one-of
    type(numeric.abserror(0.01))
  2. The dogs now pull the sleds through some thick snow and friction can no longer be ignored. Assume that the dog sleds are made from the same material, that the dogs continue pulling with the same strength and that the rope connected to the dogs is at the same angle as before.

    Perform a suitable calculation to determine which sled will experience the greater frictional force. Give a reason for your answer.

    Answer:

    The sled will experience the greater frictional force because it experiences the force.


ID is: 3679 Seed is: 4703

Physics is going to the dogs!

A team of dogs pulls two dog sleds across a frozen pond. The sled at the front has an unknown mass m2 and the sled at the back has a mass of 130 kg. The ropes attached to the dogs form an angle of 14ยฐ with the horizontal and the dogs pull with a constant force of 90 N.

While the sleds are being pulled, the front sled experiences a normal force of 780 N and the tension in the horizontal rope connecting the two sleds is T. All forms of friction can be ignored.

NOTE:

A sled is used for transport. It either has a flat bottom or long, thin strips of metal or wood attached to the bottom. A dog sled is pulled by one or more dogs (often huskies) and is used to move over ice and through snow. There are many different types of dog sled, with some being used for transport and others being used for racing.

  1. Calculate the acceleration of the sleds as well as the tension in the rope connecting the two sleds.

    INSTRUCTION:
    • Round both of your final answers to two decimal places.
    • Where appropriate, use unrounded answers from previous calculations.
    • Use the values given here for any physical constants that you may need.
    Answer:

    aโ†’=

    T=

    one-of
    type(numeric.abserror(0.01))
    one-of
    type(numeric.abserror(0.01))
  2. The dogs now pull the sleds through some thick snow and friction can no longer be ignored. Assume that the dog sleds are made from the same material, that the dogs continue pulling with the same strength and that the rope connected to the dogs is at the same angle as before.

    Perform a suitable calculation to determine which sled will experience the greater frictional force. Give a reason for your answer.

    Answer:

    The sled will experience the greater frictional force because it experiences the force.

11. Newton's third law



ID is: 3643 Seed is: 6017

Statement: Newton's third law

Use the drop-down menus below to state Newton's third law of motion in words.

Answer:

When Body A Body B, Body B exerts of magnitude on Body A.


ID is: 3643 Seed is: 3353

Statement: Newton's third law

Use the drop-down menus below to state Newton's third law of motion in words.

Answer:

When Body A Body B, Body B exerts of magnitude on Body A.



ID is: 3322 Seed is: 6795

Properties of action-reaction pairs

Newton's third law talks about action-reaction pairs. Four statements about action-reaction pairs are given to you below. For each of these statements, indicate if they are true or false.

1 Action-reaction pairs have the same magnitude.
2 Action-reaction pairs act on the same object.
3 Action-reaction pairs act in opposite directions.
4 Forces only sometimes occur in action-reaction pairs.
Answer:

Statement 1 is .

Statement 2 is .

Statement 3 is .

Statement 4 is .


ID is: 3322 Seed is: 1296

Properties of action-reaction pairs

Newton's third law talks about action-reaction pairs. Four statements about action-reaction pairs are given to you below. For each of these statements, indicate if they are true or false.

1 Action-reaction pairs occur at different times; the reaction follows the action.
2 All forces occur in action-reaction pairs.
3 Action-reaction pairs arise as an interaction between two objects.
4 Action-reaction pairs have the same magnitude.
Answer:

Statement 1 is .

Statement 2 is .

Statement 3 is .

Statement 4 is .



ID is: 1560 Seed is: 333

Newton's third law

A hornet hits the front windscreen of a moving truck. How does the magnitude of the force the hornet exerts on the windscreen compare to the magnitude of the force the windscreen exerts on the hornet?

Answer: The magnitude of the force the hornet exerts on the windscreen is .

ID is: 1560 Seed is: 170

Newton's third law

A grasshopper hits the front windscreen of a moving taxi. How does the magnitude of the force the grasshopper exerts on the windscreen compare to the magnitude of the force the windscreen exerts on the grasshopper?

Answer: The magnitude of the force the grasshopper exerts on the windscreen is .


ID is: 3790 Seed is: 4869

Identifying action-reaction pairs

A ball is falling down through the air at a constant velocity. As it falls it experiences air resistance.

One of the forces experienced by the ball is the gravitational force (Fโ†’g). Describe the force that forms an action-reaction pair with Fโ†’g. Specify its direction, which object experiences the force, and which object exerts the force.

Answer:

Fโ†’g forms an action-reaction pair with the force exerted on the by the .


ID is: 3790 Seed is: 396

Identifying action-reaction pairs

A magnet is stuck to a fridge.

One of the forces experienced by the magnet is the gravitational force (Fโ†’g). Describe the force that forms an action-reaction pair with Fโ†’g. Specify its direction, which object experiences the force, and which object exerts the force.

Answer:

Fโ†’g forms an action-reaction pair with the force exerted on the by the .



ID is: 3795 Seed is: 2278

MCQ: Identifying action-reaction pairs

A mule is trying to pull a cart with no wheels across a rough dirt path, but the cart will not move.

The following diagram shows some of the forces involved in this scenario.

KEY:

  • Fโ†’1: normal force of the cart on the ground
  • Fโ†’2: normal force of the ground on the cart
  • Fโ†’3: gravitational force of the cart on the Earth
  • Fโ†’4: gravitational force of the Earth on the cart

Consider the following two pairs of forces:

(i) Fโ†’3 and Fโ†’4
(ii) Fโ†’2 and Fโ†’4

Which of the above pairs of forces are Newton's third law action-reaction pairs?

A (i) only
B (ii) only
C Both (i) and (ii)
D Neither (i) nor (ii)
Answer:

The correct option is: .


ID is: 3795 Seed is: 6818

MCQ: Identifying action-reaction pairs

A ball is falling down through the air at a constant velocity. As it falls it experiences air resistance.

The following diagram shows some of the forces involved in this scenario.

KEY:

  • Fโ†’1: air resistance of the air molecules on the ball
  • Fโ†’2: gravitational force of the ball on the Earth
  • Fโ†’3: air resistance of the ball on the air molecules
  • Fโ†’4: gravitational force of the Earth on the ball

Consider the following two pairs of forces:

(i) Fโ†’2 and Fโ†’3
(ii) Fโ†’2 and Fโ†’4

Which of the above pairs of forces are Newton's third law action-reaction pairs?

A (i) only
B (ii) only
C Both (i) and (ii)
D Neither (i) nor (ii)
Answer:

The correct option is: .



ID is: 3793 Seed is: 8946

Action-reaction pairs

A ball is falling down through the air at a constant velocity. As it falls it experiences air resistance.

Iminathi and Kevin draw a diagram and show some of the forces involved in this scenario.

KEY:

  • Fโ†’1: air resistance of the ball on the air molecules
  • Fโ†’2: gravitational force of the ball on the Earth
  • Fโ†’3: gravitational force of the Earth on the ball
  • Fโ†’4: air resistance of the air molecules on the ball
  1. Iminathi says that Fโ†’1 and Fโ†’4 can cancel each other out. This is Iminathi's explanation of why she thinks that Fโ†’1 and Fโ†’4 can cancel each other out:

    Fโ†’1 and Fโ†’4 form an action-reaction pair of forces. Forces in action-reaction pairs are always equal in magnitude and opposite in direction. So they will cancel each other out because their vector sum is zero. Which means that the net vertical force experienced by the ball will be zero.

    Wow! That sounds pretty convincing, but Kevin disagrees and says that Fโ†’1 and Fโ†’4 cannot cancel each other out.

    Determine whether Iminathi is correct or incorrect and give a reason from the table below.

    Fโ†’1 and Fโ†’4 ...

    A are not equal in magnitude
    B do not both act on the ball
    C are not opposite in direction
    D are not an action-reaction pair
    Answer:

    Iminathi is because Fโ†’1 and Fโ†’4 .

  2. Which pair of forces does cancel out to keep the ball in equilibrium?

    Answer:

    and will cancel each other out.


ID is: 3793 Seed is: 8900

Action-reaction pairs

A ball is falling down through the air at a constant velocity. As it falls it experiences air resistance.

Adaeze and Lethabo draw a diagram and show some of the forces involved in this scenario.

KEY:

  • Fโ†’1: air resistance of the air molecules on the ball
  • Fโ†’2: gravitational force of the ball on the Earth
  • Fโ†’3: air resistance of the ball on the air molecules
  • Fโ†’4: gravitational force of the Earth on the ball
  1. Adaeze says that Fโ†’1 and Fโ†’3 can cancel each other out. This is Adaeze's explanation of why she thinks that Fโ†’1 and Fโ†’3 can cancel each other out:

    Fโ†’1 and Fโ†’3 form an action-reaction pair of forces. Forces in action-reaction pairs are always equal in magnitude and opposite in direction. So they will cancel each other out because their vector sum is zero. Which means that the net vertical force experienced by the ball will be zero.

    Wow! That sounds pretty convincing, but Lethabo disagrees and says that Fโ†’1 and Fโ†’3 cannot cancel each other out.

    Determine whether Adaeze is correct or incorrect and give a reason from the table below.

    Fโ†’1 and Fโ†’3 ...

    A are not opposite in direction
    B are not equal in magnitude
    C do not both act on the ball
    D are not an action-reaction pair
    Answer:

    Adaeze is because Fโ†’1 and Fโ†’3 .

  2. Which pair of forces does cancel out to keep the ball in equilibrium?

    Answer:

    and will cancel each other out.



ID is: 3287 Seed is: 804

Multiple choice: Newton's laws

A body with mass 2m exerts a force of magnitude F on a second body with mass m. This is a net force which causes the second body to have an acceleration of magnitude a.

Which one of the following statements is true regarding the force that the second object exerts on the first object and the acceleration experienced by the first object?

A The force has magnitude F and the acceleration has magnitude 12a.
B The force has magnitude F and the acceleration has magnitude a.
C The force has magnitude 12F and the acceleration has magnitude 12a.
D The force has magnitude 12F and the acceleration has magnitude a.
Answer: The correct option is: .

ID is: 3287 Seed is: 5362

Multiple choice: Newton's laws

A body with mass m exerts a force of magnitude F on a second body with mass 5m. This is a net force which causes the second body to have an acceleration of magnitude a.

Which one of the following statements is true regarding the force that the second object exerts on the first object and the acceleration experienced by the first object?

A The force has magnitude 5F and the acceleration has magnitude a.
B The force has magnitude F and the acceleration has magnitude a.
C The force has magnitude F and the acceleration has magnitude 5a.
D The force has magnitude 5F and the acceleration has magnitude 5a.
Answer: The correct option is: .

12. Forces between masses

13. Newton's universal law of gravitation



ID is: 3644 Seed is: 576

Statement: Newton's universal law of gravitation

Adapted from DBE Nov 2015 & 2016 Grade 11, P1, Q5
Physical constants ยท Physics formulas

State Newton's universal law of gravitation in words.

Answer:

Every body in the universe every other body with a gravitational force that is the their masses and the of the distance between their centres.


ID is: 3644 Seed is: 5776

Statement: Newton's universal law of gravitation

Adapted from DBE Nov 2015 & 2016 Grade 11, P1, Q5
Physical constants ยท Physics formulas

State Newton's universal law of gravitation in words.

Answer:

Every body in the universe every other body with a gravitational force that is the their masses and the of the distance between their centres.



ID is: 3807 Seed is: 8283

Understanding Newton's universal law of gravitation

The following relationship is an important equation in mechanics:

Fg=Gm1m2d2

It is the mathematical form of Newton's universal law of gravitation.

  1. What does the symbol G stand for?

    A magnitude of the gravitational force
    B gravitational acceleration
    C universal gravitational constant
    D g-force
    Answer:

    The meaning of G is .

  2. What is the SI unit used to measure d?

    Answer:

    The SI unit used to measure d is .


ID is: 3807 Seed is: 5861

Understanding Newton's universal law of gravitation

The following relationship is an important equation in mechanics:

Fg=Gm1m2d2

It is the mathematical form of Newton's universal law of gravitation.

  1. What does the symbol Fg stand for?

    A magnitude of the gravitational force
    B gravitational acceleration
    C g-force
    D universal gravitational constant
    Answer:

    The meaning of Fg is .

  2. What is the SI unit in which we measure m1?

    Answer:

    The SI unit in which we measure m1 is .



ID is: 1466 Seed is: 3428

Gravitational force between planets

When the planet Neptune is furthest from Earth it is 4,41ร—1012 m away. The planet Neptune has a mass of 1,02ร—1026 kg, and the Earth has a mass of 5,97ร—1024 kg.

What is the magnitude of the gravitational force between the planet Neptune and the Earth?

INSTRUCTIONS:
  • Write your answer in scientific notation and then round it to two decimal places.
  • You must use these values for any physical constants that you might need.
Answer:

Fg= N

numeric

ID is: 1466 Seed is: 8215

Gravitational force between planets

When the planet Venus is closest to Earth it is 38 200 000 000,0 m away. The planet Venus has a mass of 4,87ร—1024 kg, and the Earth has a mass of 5,97ร—1024 kg.

What is the magnitude of the gravitational force between the planet Venus and the Earth?

INSTRUCTIONS:
  • Write your answer in scientific notation and then round it to two decimal places.
  • You must use these values for any physical constants that you might need.
Answer:

Fg= N

numeric


ID is: 3320 Seed is: 499

Acceleration due to gravity on any planet

Phetoho travels in a spaceship to Europa (a moon of Jupiter). He needs to know what kind of conditions to prepare for. In particular, he needs to know the average acceleration due to gravity on the surface of Europa in order to land safely. The mass of Europa is 4,778ร—1022 kg and it has a radius of 1 548,9 km.

Calculate the magnitude of the acceleration due gravity near the surface of Europa.

INSTRUCTIONS:
  • Round your answer to three decimal places.
  • You must use these values for any physical constants you might need.
Answer:

gEuropa =

one-of
type(numeric.abserror(0.001))

ID is: 3320 Seed is: 43

Acceleration due to gravity on any planet

Ekueme travels in a spaceship to Callisto (a moon of Jupiter). He needs to know what kind of conditions to prepare for. In particular, he needs to know the average acceleration due to gravity on the surface of Callisto in order to land safely. The mass of Callisto is 1,080ร—1023 kg and it has a radius of 2 424,4 km.

Calculate the magnitude of the acceleration due gravity near the surface of Callisto.

INSTRUCTIONS:
  • Round your answer to two decimal places.
  • You must use these values for any physical constants you might need.
Answer:

gCallisto =

one-of
type(numeric.abserror(0.01))


ID is: 1561 Seed is: 1168

Terminology: Newton's laws

Complete the definition/law or provide the term asked for:

TIP: You can't just make the statement true in a specific case. If it's a definition, then it needs to be generally true.
  1. Newton's _______ law of motion states: If body A exerts a force on body B, then body B exerts a force of equal magnitude on body A, but in the opposite direction.

    Answer:
    one-of
    type(string.nocase)
  2. Newton's _______ law of motion states: If a resultant force acts on a body, it will cause the body to accelerate in the direction of the resultant force. The acceleration of the body will be directly proportional to the resultant force and inversely proportional to the mass of the body.

    Answer:
    one-of
    type(string.nocase)

ID is: 1561 Seed is: 7388

Terminology: Newton's laws

Complete the definition/law or provide the term asked for:

TIP: You can't just make the statement true in a specific case. If it's a definition, then it needs to be generally true.
  1. Name, Fโ†’N, the force exerted by a surface on an object in contact with it.

    Answer:
    one-of
    type(string.nocase)
  2. Name the force that opposes the motion of a object in contact with a surface and it acts parallel to the surface the object is in contact with.

    Answer:
    one-of
    type(string.nocase)


ID is: 1542 Seed is: 900

Newton's universal law of gravity

Two objects with masses of 2,5ร—1017 kg and 7,6ร—1017 kg exert a gravitational force on each other of 2,62ร—1015 N. What is the distance between the centres of the two objects?

INSTRUCTION:
  • Write your answer in scientific notation and then round it to two decimal places.
  • Use any physical constants you may need as listed here.
Answer:

d= m

numeric

ID is: 1542 Seed is: 6423

Newton's universal law of gravity

Two objects are 32 400 m apart. One of the objects has a mass of 4,1ร—1017 kg and they exert a gravitational force of 1,07ร—1016 N on each other. What is the mass of the second object?

INSTRUCTION:
  • Write your answer in scientific notation and then round it to two decimal places.
  • Use any physical constants you may need as listed here.
Answer:

m2= kg

numeric


ID is: 3859 Seed is: 2835

Gravitational forces in space

In a distant galaxy, two planets, X and Y, are interacting gravitationally. Planet X has a mass of 4,44ร—1028 kg and Planet Y has a mass of 8,39ร—1023 kg. When the distance between them is d, Planet X exerts a gravitational force of 8,24ร—1022 N on Planet Y.

  1. Determine the distance between the planets (d).

    INSTRUCTIONS:
    • Write your answer in scientific notation and then round it to two decimal places.
    • Use these physical constants for any calculations.
    Answer:

    d=

    numeric
    1. What is the gravitational force exerted on Planet X by Planet Y?

      A The force points towards Y and away from X, and has a magnitude equal to 8,24ร—1022 N.
      B The force points towards X and away from Y, and has a magnitude less than 8,24ร—1022 N.
      C The force points towards X and away from Y, and has a magnitude equal to 8,24ร—1022 N.
      D The force points towards Y and away from X, and has a magnitude less than 8,24ร—1022 N.
    2. Which of Newton's laws of motion should you use to answer the above question?
    Answer:
    1. The gravitational force of Y on X is .
    2. The law to use is Newton's law of motion.

ID is: 3859 Seed is: 2522

Gravitational forces in space

In a distant galaxy, two asteroids, X and Y, are interacting gravitationally. Asteroid X has a mass of 1,83ร—1017 kg and Asteroid Y has a mass mY. When the distance between them is 8,34ร—108 m, Asteroid X exerts a gravitational force of 6,35ร—104 N on Asteroid Y.

  1. Determine the mass of Asteroid Y (mY).

    INSTRUCTIONS:
    • Write your answer in scientific notation and then round it to two decimal places.
    • Use these physical constants for any calculations.
    Answer:

    mY=

    numeric
    1. What is the gravitational force exerted on Asteroid X by Asteroid Y?

      A The force points towards Y and away from X, and has a magnitude equal to 6,35ร—104 N.
      B The force points towards Y and away from X, and has a magnitude less than 6,35ร—104 N.
      C The force points towards X and away from Y, and has a magnitude less than 6,35ร—104 N.
      D The force points towards X and away from Y, and has a magnitude equal to 6,35ร—104 N.
    2. Which of Newton's laws of motion should you use to answer the above question?
    Answer:
    1. The gravitational force of Y on X is .
    2. The law to use is Newton's law of motion.


ID is: 3860 Seed is: 6307

Comets!

Kelly is an astronomer and she is studying comets with different types of trajectory. One comet she is studying has an elliptical orbit around a star somewhere in the Milky Way.

NOTE: See how the tail of the comet points directly away from the star? The tail doesn't tell you anything about the direction of motion of the comet!
    1. Identify the type of force experienced by the comet at Point A.
    2. How does the force that the comet exerts on the star compare to the force that the star exerts on the comet at Point B?
    Answer:
    1. At Point A, the comet experiences force.
    2. At Point B, the magnitude of the force that the comet exerts on the star is the magnitude of the force that the star exerts on the comet. These forces are in .
  1. How does the acceleration experienced by the comet at Point C compare to the acceleration at Point D? Refer to the magnitudes as well as the directions of the accelerations as part of your answer.

    Answer:

    The magnitude of the acceleration at Point C is the magnitude of the acceleration at Point D.

    of the accelerations point . At Point C the acceleration points and at Point D the acceleration points .


ID is: 3860 Seed is: 7220

Comets!

Sindisiwe is an astronomer and she is studying comets with different types of trajectory. One comet she is studying has a parabolic orbit around a star somewhere in the Milky Way.

NOTE: See how the tail of the comet points directly away from the star? The tail doesn't tell you anything about the direction of motion of the comet!
    1. Identify the type of force experienced by the comet at Point P.
    2. How does the force that the comet exerts on the star compare to the force that the star exerts on the comet at Point Q?
    Answer:
    1. At Point P, the comet experiences force.
    2. At Point Q, the magnitude of the force that the comet exerts on the star is the magnitude of the force that the star exerts on the comet. These forces are in .
  1. How does the acceleration experienced by the comet at Point R compare to the acceleration at Point S? Refer to the magnitudes as well as the directions of the accelerations as part of your answer.

    Answer:

    The magnitude of the acceleration at Point R is the magnitude of the acceleration at Point S.

    of the accelerations point . At Point R the acceleration points and at Point S the acceleration points .



ID is: 3861 Seed is: 1485

Planetary orbits

Adebanke is an astronomer and she is studying a planet which is orbiting a star in the Milky Way galaxy. The planet is a massive gas giant and has a mass of 6,54ร—1028 kg and its parent star has a mass of 2,95ร—1030 kg. Adebanke plots the position of the planet and its star on a Cartesian plane. The origin of the Cartesian plane is located at the centre of the star. Adebanke uses this graph to establish that the planet traces out an elliptical orbit around the sun.

On a particular date, Adebanke observes the planet at the coordinate (78,7;โˆ’63,8) million km relative to the sun.

Calculate the gravitational force that the planet exerts on the star.

INSTRUCTIONS:
  • Give the magnitude of the force to two decimal places, in scientific notation.
  • Give the direction of the force, to one decimal place, as an angle measured anti-clockwise from the positive x-axis.
  • Use these values for any physical constants you might need.
Answer:

Fโ†’g= at ยฐ anti-clockwise from the positive x-axis.

TIP: Do not give the angle as a bearing! You need to work with the angle the same way you would in maths.
numeric
one-of
type(numeric.abserror(0.1))

ID is: 3861 Seed is: 4000

Planetary orbits

Aisha is an astronomer and she is studying a planet which is orbiting a star in the Milky Way galaxy. The planet is a massive gas giant and has a mass of 9,42ร—1027 kg and its parent star has a mass of 6,85ร—1031 kg. Aisha plots the position of the planet and its star on a Cartesian plane. The origin of the Cartesian plane is located at the centre of the star. Aisha uses this graph to establish that the planet traces out an elliptical orbit around the sun.

On a particular date, Aisha observes the planet at the coordinate (โˆ’858;โˆ’437) million km relative to the sun.

Calculate the gravitational force that the planet exerts on the star.

INSTRUCTIONS:
  • Give the magnitude of the force to two decimal places, in scientific notation.
  • Give the direction of the force, to one decimal place, as an angle measured anti-clockwise from the positive x-axis.
  • Use these values for any physical constants you might need.
Answer:

Fโ†’g= at ยฐ anti-clockwise from the positive x-axis.

TIP: Do not give the angle as a bearing! You need to work with the angle the same way you would in maths.
numeric
one-of
type(numeric.abserror(0.1))


ID is: 3827 Seed is: 1843

Losing weight on holiday

Thandolwethu is on holiday in Sydney (in Australia) which is at an altitude of 37 m above sea-level. She climbs the stairs to the top of the Sydney Tower, which has a total height of 309 m above the ground. Thandolwethu has a mass of 78 kg.

The mass of the Earth is 5,972ร—1024 kg. The distance from the centre of the Earth to sea-level is 6 371 km .

INSTRUCTIONS:
  • Round all numerical answers to five decimal places.
  • You cannot assume that g=9,8 mยทsโˆ’2 anywhere in this question!
  1. What is Thandolwethu's weight at the bottom of the Sydney Tower?

    Answer:

    Thandolwethu's weight is at the bottom.

    one-of
    type(numeric.abserror(1e-05))
  2. Thandolwethu has been studying physics during her holiday and knows that the gravitational force decreases in magnitude as distance increases. She wonders what fraction of her weight she will have lost during her climb up the Sydney Tower.

    1. What percentage of her weight does Thandolwethu lose when climbing to the top of the Sydney Tower?
    2. Does Thandolwethu lose mass when climbing to the top of the Sydney Tower?
    Answer:
    1. Thandolwethu loses % of her weight.
    2. Thandolwethu lose any mass.
    one-of
    type(numeric.abserror(5e-05))

ID is: 3827 Seed is: 8230

Losing weight on holiday

Ikenna is on holiday in Kuala Lumpur (in Malaysia) which is at an altitude of 37 m above sea-level. He climbs the stairs to the top of the Menara Telekom (a very tall building), which has a total height of 310 m above the ground. Ikenna has a mass of 81 kg.

The mass of the Earth is 5,972ร—1024 kg. The distance from the centre of the Earth to sea-level is 6 371 km .

INSTRUCTIONS:
  • Round all numerical answers to five decimal places.
  • You cannot assume that g=9,8 mยทsโˆ’2 anywhere in this question!
  1. What is Ikenna's weight at the bottom of the Menara Telekom?

    Answer:

    Ikenna's weight is at the bottom.

    one-of
    type(numeric.abserror(1e-05))
  2. Ikenna has been studying physics during his holiday and knows that the gravitational force decreases in magnitude as distance increases. He wonders what fraction of his weight he will have lost during his climb up the Menara Telekom.

    1. What percentage of his weight does Ikenna lose when climbing to the top of the Menara Telekom?
    2. Does Ikenna lose mass when climbing to the top of the Menara Telekom?
    Answer:
    1. Ikenna loses % of his weight.
    2. Ikenna lose any mass.
    one-of
    type(numeric.abserror(5e-05))


ID is: 3826 Seed is: 3040

Space rocket

A space rocket of mass 21 100 kg is orbiting Dione (a moon of Saturn) at a height of 220 km above the surface of Dione. The rocket has switched off its engines and is effectively in free-fall as it orbits in a circular path.

Dione has a mass of 1,10ร—1021 kg and a radius of 5,614ร—102 km.

  1. Calculate the force of gravity experienced by the rocket.

    INSTRUCTIONS:
    • Give your answer rounded to three decimal places in scientific notation.
    • You must use these values for any physical constants you might need.
    Answer:

    Fโ†’g=

    numeric
  2. Calculate the acceleration of the rocket as it orbits Dione.

    INSTRUCTIONS:
    • Round your answer to three decimal places.
    • Where necessary, use unrounded values from Question 1.
    Answer:

    aโ†’= .

    one-of
    type(numeric.abserror(0.001))
  3. The rocket orbits Dione with a constant speed. How is it possible for the rocket to have a non-zero acceleration and maintain a constant speed?

    A The rocket constantly needs to fire the engines to brake to maintain a constant speed.
    B It's not possible. The acceleration of the rocket must be zero.
    C The acceleration changes the direction of motion, but not the speed of the rocket.
    D It's not possible. The rocket's speed will increase.
    Answer:

    The correct option is:


ID is: 3826 Seed is: 289

Space rocket

A space rocket of mass 23 500 kg is orbiting Umbriel (a moon of Uranus) at a height of 310 km above the surface of Umbriel. The rocket has switched off its engines and is effectively in free-fall as it orbits in a circular path.

Umbriel has a mass of 1,20ร—1021 kg and a radius of 5,847ร—102 km.

  1. Calculate the force of gravity experienced by the rocket.

    INSTRUCTIONS:
    • Give your answer rounded to three decimal places in scientific notation.
    • You must use these values for any physical constants you might need.
    Answer:

    Fโ†’g=

    numeric
  2. Calculate the acceleration of the rocket as it orbits Umbriel.

    INSTRUCTIONS:
    • Round your answer to four decimal places.
    • Where necessary, use unrounded values from Question 1.
    Answer:

    aโ†’= .

    one-of
    type(numeric.abserror(0.0001))
  3. The rocket orbits Umbriel with a constant speed. How is it possible for the rocket to have a non-zero acceleration and maintain a constant speed?

    A It's not possible. The rocket's speed will increase.
    B It's not possible. The acceleration of the rocket must be zero.
    C The rocket constantly needs to fire the engines to brake to maintain a constant speed.
    D The acceleration changes the direction of motion, but not the speed of the rocket.
    Answer:

    The correct option is:

14. Weight and mass



ID is: 3798 Seed is: 287

Units of mass and weight

Use the dropdown menus to provide the missing units in the the scenario described below.

Answer: An astronaut exploring Saturn (a planet) has a weight of 1 044 and a mass of 100 .

ID is: 3798 Seed is: 4940

Units of mass and weight

Use the dropdown menus to provide the missing units in the the scenario described below.

Answer: An astronaut exploring Mercury (a planet) has a mass of 87 and a weight of 322 .


ID is: 3799 Seed is: 652

Mass and weight

Mass and weight are related to each other, but they are different quantities in physics.

The lists below summarise some important differences between mass and weight. But each list is missing two pieces of information! Complete the lists by selecting the correct choices.

Answer:

Mass:

  • is an amount of
  • has the symbol
  • is measured in SI units of kg
  • does not depend on location

Weight:

  • is an amount of
  • has the symbol
  • is measured in SI units of N
  • does depend on location

ID is: 3799 Seed is: 1636

Mass and weight

Mass and weight are related to each other, but they are different quantities in physics.

The lists below summarise some important differences between mass and weight. But each list is missing two pieces of information! Complete the lists by selecting the correct choices.

Answer:

Mass:

  • is an amount of matter
  • has the symbol
  • is measured in SI units of kg
  • depend on location

Weight:

  • is an amount of force
  • has the symbol
  • is measured in SI units of N
  • depend on location


ID is: 3656 Seed is: 4129

Understanding Fg=mg

The relationship Fg=mg is an important equation in mechanics.

  1. What does the symbol m stand for?

    Answer:

    The symbol m stands for .

  2. What is the SI unit in which we measure Fg?

    Answer:

    The SI unit in which we measure Fg is .


ID is: 3656 Seed is: 8506

Understanding Fg=mg

The relationship Fg=mg is a useful equation in mechanics.

  1. What does the symbol g stand for?

    Answer:

    The symbol g stands for .

  2. What is the SI unit used to measure Fg?

    Answer:

    The SI unit used to measure Fg is .



ID is: 3646 Seed is: 7827

Definitions: weight and mass

Use the drop-down menus below to define weight and mass.

Answer:

Weight is the the Earth (or any planet-like body) exerts on any object on or near its surface. The SI unit for weight is the .

Mass is a measure of how much is inside an object. The SI unit for mass is the .


ID is: 3646 Seed is: 6128

Definitions: weight and mass

Use the drop-down menus below to define weight and mass.

Answer:

Weight is the the Earth (or any planet-like body) exerts on any object on or near its surface. The SI unit for weight is the .

Mass is a measure of how much is inside an object. The SI unit for mass is the .



ID is: 3637 Seed is: 5402

The relationship between g, Fg, and m

Gravitational acceleration (g), gravitational force (Fg), and mass (m) are three important quantities in mechanics.

Which one of the following equations correctly represents the relationship between these quantities?

A Fg=gm
B Fg=mg
C Fg=mg
Answer:

ID is: 3637 Seed is: 1130

The relationship between m, g, and Fg

Mass (m), gravitational acceleration (g), and gravitational force (Fg) are three important quantities in mechanics.

Which one of the following equations correctly represents the relationship between these quantities?

A g=Fgm
B g=mFg
C g=Fgm
Answer:


ID is: 3813 Seed is: 6306

Mass and weight on Earth

A box on the Earth's surface has a mass of 56 kg.

Calculate the weight of the box.

INSTRUCTIONS:
  • Round your answer to one decimal place.
  • Choose the correct unit for weight from the drop-down menu.
  • Use any physical constants that you may need as listed here.
Answer: The weight of the box is .
one-of
type(numeric.abserror(0.1))

ID is: 3813 Seed is: 21

Mass and weight on Earth

A box on the Earth's surface has a mass of 77 kg.

Calculate the weight of the box.

INSTRUCTIONS:
  • Round your answer to one decimal place.
  • Choose the correct unit for weight from the drop-down menu.
  • Use any physical constants that you may need as listed here.
Answer: The weight of the box is .
one-of
type(numeric.abserror(0.1))


ID is: 3645 Seed is: 6089

True weight, apparent weight and weightlessness

Match the descriptions in the table below to the concepts of true weight, apparent weight, and weightlessness.

X Always equal to mg, where m is the mass of an object and g is the local acceleration due to gravity.
Y A feeling experienced when the only force acting on the body is the gravitational force.
Z The weight felt or perceived by a body.
Answer:
  • True weight:
  • Apparent weight:
  • Weightlessness:

ID is: 3645 Seed is: 6570

True weight, apparent weight and weightlessness

Match the descriptions in the table below to the concepts of true weight, apparent weight, and weightlessness.

X The force a body exerts on the surface it rests on.
Y Always equal to mg, where m is the mass of an object and g is the local acceleration due to gravity.
Z A feeling experienced when a body is in free-fall.
Answer:
  • True weight:
  • Apparent weight:
  • Weightlessness:


ID is: 3427 Seed is: 3325

Calculating weight on other planets

Monique is exploring Dione (a moon of Saturn). She is expecting a container of supplies with a mass of 2 130 kg to be delivered to Dione so she can continue her mission. Dione has a gravitational acceleration of 0,23 mยทsโˆ’2.

Calculate the gravitational force acting on the container on Dione.

INSTRUCTIONS:
  • Round your answer to two decimal places.
  • You must use these values for any physical constants you might need.
Answer:

Fg,Dione=

one-of
type(numeric.abserror(0.01))

ID is: 3427 Seed is: 555

Calculating weight on other planets

Fadekemi is exploring Ganymede (a moon of Jupiter). She is expecting a package of supplies with a mass of 6 000 kg to be delivered to Ganymede so she can continue her mission. Ganymede has a gravitational acceleration of 1,43 mยทsโˆ’2.

Calculate the gravitational force acting on the package on Ganymede.

INSTRUCTIONS:
  • Round your answer to two decimal places.
  • You must use these values for any physical constants you might need.
Answer:

Fg,Ganymede=

one-of
type(numeric.abserror(0.01))


ID is: 3475 Seed is: 4465

Gravity on other planets

Lami wants to know how the solar system evolved to its current state. While exploring the solar system, she decides to land on Europa (a moon of Jupiter).

  1. In order to land the spacecraft safely on the surface of Europa, Lami needs to gather some additional information. The mass of Europa is 4,785ร—1022 kg and it has a radius of 1 565,7 km.

    Calculate the magnitude of the acceleration due gravity near the surface of Europa.

    INSTRUCTION:
    • Round your answer to two decimal places.
    • Use the values for any physical constants you may need, as listed here.
    Answer:

    gEuropa=

    one-of
    type(numeric.abserror(0.01))
  2. After safely landing on Europa, Lami analyses the composition of an interesting section of bedrock. The section of bedrock has a mass of 20 000 kg.

    Calculate the weight of the section of bedrock.

    INSTRUCTION:
    • Where applicable, use unrounded values from Question 1.
    • Round your answer to the nearest 100 N.
    Answer:

    Fg=

    numeric

ID is: 3475 Seed is: 5414

Gravity on other planets

Melanie wants to know how the solar system evolved to its current state. While exploring the solar system, she decides to land on Mercury (a planet).

  1. In order to land the spacecraft safely on the surface of Mercury, Melanie needs to gather some additional information. The mass of Mercury is 3,278ร—1023 kg and it has a radius of 2 460,6 km.

    Calculate the magnitude of the acceleration due gravity near the surface of Mercury.

    INSTRUCTION:
    • Round your answer to two decimal places.
    • Use the values for any physical constants you may need, as listed here.
    Answer:

    gMercury=

    one-of
    type(numeric.abserror(0.01))
  2. After safely landing on Mercury, Melanie analyses the composition of an interesting boulder. The boulder has a weight of 134 200 N.

    Calculate the mass of the boulder.

    INSTRUCTION:
    • Where applicable, use unrounded values from Question 1.
    • Round your answer to the nearest 100 kg.
    Answer:

    m=

    numeric


ID is: 3862 Seed is: 1653

Experiment: Weight on other planets

Gabisile is an astronaut. She performs an experiment to see how her weight varies from place to place in the solar system. She takes her mom's bathroom scale and sets off in her spaceship to measure her weight near the surface of different planets, moons, and asteroids in the solar system.

She obtains the following results:

Location Weight (N)
Earth 768,4
Saturn (a planet) 818,5
Uranus (a planet) 695,1
Tethys (a moon of Saturn) 11,4
Ceres (an asteroid and dwarf planet) 21,9
  1. Identify the independent, the dependent, and a fixed variable in Gabisile's investigation:

    Answer:
    Independent
    Dependent
    Fixed
  2. Here is Gabisile's data table again:

    Location Weight (N)
    Earth 768,4
    Saturn (a planet) 818,5
    Uranus (a planet) 695,1
    Tethys (a moon of Saturn) 11,4
    Ceres (an asteroid and dwarf planet) 21,9

    Use this table to calculate:

    1. Gabisile's mass (m).
    2. The local acceleration due to gravity on Saturn (gSaturn).
    3. The mass of Saturn (MSaturn) if its radius is 6,027ร—107 m.
    INSTRUCTIONS:
    • Round all answers to two decimal places.
    • The mass of Saturn should be in scientific notation.
    • You must use these values for any physical constants required in your calculations.
    • You might find some of these physics formulas useful.
    Answer:
    1. m=
    2. gSaturn=
    3. MSaturn=
    one-of
    type(numeric.abserror(0.01))
    one-of
    type(numeric.abserror(0.01))
    one-of
    type(numeric.scientific.abserror(1e+24))
  3. Gabisile uses the data from the table to produce a graph. What type of graph should Gabisile use? Give a reason for your answer.

    Answer: Gabisile should use a because the data is and make up a whole.

ID is: 3862 Seed is: 9838

Experiment: Weight on other planets

Hannelie is an astronaut. She performs an experiment to see how her weight varies from place to place in the solar system. She takes her dad's bathroom scale and sets off in her spaceship to measure her weight near the surface of different planets, moons, and asteroids in the solar system.

She obtains the following results:

Location Weight (N)
Earth 705,7
Ceres (an asteroid and dwarf planet) 20,2
Mars (a planet) 267,4
Venus (a planet) 638,5
Rhea (a moon of Saturn) 19,1
  1. Identify the independent, the dependent, and a fixed variable in Hannelie's investigation:

    Answer:
    Independent
    Dependent
    Fixed
  2. Here is Hannelie's data table again:

    Location Weight (N)
    Earth 705,7
    Ceres (an asteroid and dwarf planet) 20,2
    Mars (a planet) 267,4
    Venus (a planet) 638,5
    Rhea (a moon of Saturn) 19,1

    Use this table to calculate:

    1. Hannelie's mass (m).
    2. The local acceleration due to gravity on Rhea (gRhea).
    3. The radius of Rhea (RRhea) if its mass is 2,317ร—1021 kg.
    INSTRUCTIONS:
    • Round all answers to two decimal places.
    • The radius of Rhea should be in scientific notation.
    • You must use these values for any physical constants required in your calculations.
    • You might find some of these physics formulas useful.
    Answer:
    1. m=
    2. gRhea=
    3. RRhea=
    one-of
    type(numeric.abserror(0.01))
    one-of
    type(numeric.abserror(0.01))
    one-of
    type(numeric.scientific.abserror(1e+03))
  3. Hannelie uses the data from the table to produce a graph. What type of graph should Hannelie use? Give a reason for your answer.

    Answer: Hannelie should use a because the data is and make up a whole.


ID is: 3814 Seed is: 7283

Apparent weight, true weight, and weightlessness

A girl is sitting in a roller coaster which is accelerating downwards.

  1. How does the apparent weight of the girl compare to her true weight?
  2. Does the girl experience weightlessness?
Answer:
  1. The girl's apparent weight is her true weight.
  2. The girl experience weightlessness.

ID is: 3814 Seed is: 5512

Apparent weight, true weight, and weightlessness

An astronaut is standing in a rocket which is accelerating downwards (towards the surface of the Earth) with an acceleration less than 9,8 mยทsโˆ’2.

  1. How does the apparent weight of the astronaut compare to her true weight?
  2. Does the astronaut experience weightlessness?
Answer:
  1. The astronaut's apparent weight is her true weight.
  2. The astronaut experience weightlessness.

15. Proportional reasoning with gravity



ID is: 1541 Seed is: 7077

Effect of distance on gravitational force

A goose is 9 km above the surface of the Earth. If its distance above the Earth is greatly decreased, what happens to the mass of the goose?

Answer:

The mass of the goose would .


ID is: 1541 Seed is: 3710

Effect of distance on gravitational force

A goose is 5 km above the surface of the Earth. If its distance above the Earth is greatly increased, what happens to the mass of the goose?

Answer:

The mass of the goose would .



ID is: 1492 Seed is: 849

Comparing weights on different planets

A safe filled with diamonds has a mass of 446 kg. Planet Zirgon has the same mass as the Earth but has half the radius of the Earth. What would the safe weigh on Zirgon, if the gravitational acceleration on Earth is 9,8 mยทsโˆ’2?

INSTRUCTION: Round your answer to one decimal place.
Answer: wZ= N
one-of
type(numeric.abserror(0.1))

ID is: 1492 Seed is: 8408

Comparing weights on different planets

A woman has a mass of 70 kg. Planet Targ is the same size as the Earth but has four times the mass of the Earth. What would the woman weigh on Targ, if the gravitational acceleration on Earth is 9,8 mยทsโˆ’2?

INSTRUCTION: Round your answer to one decimal place.
Answer: wT= N
one-of
type(numeric.abserror(0.1))


ID is: 1477 Seed is: 5720

Effect of mass on gravitational force

A satellite with mass MS orbits the Earth, and experiences a gravitational force of F. The satellite is hit by a meteoroid and part of the satellite breaks off. The new mass of the satellite is 12MS.

What will the new gravitational force on the satellite be?

INSTRUCTION: Write your answer as an exact fraction of the force F before the accident.
Answer: Fafter= F
numeric

ID is: 1477 Seed is: 7758

Effect of mass on gravitational force

A satellite with mass MS orbits the Earth, and experiences a gravitational force of F. The satellite is hit by a meteoroid and part of the satellite breaks off. The new mass of the satellite is 15MS.

What will the new gravitational force on the satellite be?

INSTRUCTION: Write your answer as an exact fraction of the force F before the accident.
Answer: Fafter= F
numeric


ID is: 1479 Seed is: 5568

Effect of mass on gravitational force

The International Space Station (ISS) has a mass M, as it orbits the Earth, it experiences a gravitational force of F. A space shuttle docks onto the ISS. The gravitational force the ISS experiences once the mass of the shuttle is added increases by a factor of 6.

What is the new combined mass of the ISS and the docked shuttle? Write your answer in terms of the original mass M of the ISS.

Answer: Mnew= M
numeric

ID is: 1479 Seed is: 1726

Effect of mass on gravitational force

The International Space Station (ISS) has a mass M, as it orbits the Earth, it experiences a gravitational force of F. A space shuttle docks onto the ISS. The gravitational force the ISS experiences once the mass of the shuttle is added increases by a factor of 4.

What is the new combined mass of the ISS and the docked shuttle? Write your answer in terms of the original mass M of the ISS.

Answer: Mnew= M
numeric


ID is: 3808 Seed is: 3252

Effect of mass and distance on the gravitational force

Two moons are gravitationally attracted to each other in deep space.

Consider a second scenario where, compared to the first scenario,

  • the distance between the two moons is smaller,
  • and both masses are larger.

The above images are not perfectly to scale.

How will the gravitational force between the two moons in each scenario compare?

The gravitational force in the second scenario will be:

A stronger
B weaker
C the same
D impossible to know
Answer: The correct option is:

ID is: 3808 Seed is: 4183

Effect of mass and distance on the gravitational force

Two moons are gravitationally attracted to each other in deep space.

Consider a second scenario where, compared to the first scenario,

  • the distance between the two moons is greater,
  • and one mass is smaller while the other mass is the same.

The above images are not perfectly to scale.

How will the gravitational force between the two moons in each scenario compare?

The gravitational force in the second scenario will be:

A stronger
B weaker
C the same
D impossible to know
Answer: The correct option is:


ID is: 3659 Seed is: 4953

Proportional reasoning with Fg, m, and g

The relationship Fg=mg is an important equation in mechanics. It is the mathematical statement that shows the relationship between weight, mass, and a planet's local gravitational acceleration.

Consider two systems on the same planet (they have the same local gravitational acceleration).

  1. What can we say about the relationship between the weight of each system and the mass?

    Answer:

    The weight is the mass.

  2. Consider the options below and choose the one that represents the relationship between weight and mass symbolically:

    A Fgโˆ1m
    B Fgโˆm
    C Fg>m
    D Fg<m
    E Fg=m
    Answer:

    The correct option is .

  3. The mass of the second system is 8 times bigger than the mass of the first system. How does the weight of the second system compare to the weight of the first system?

    Answer:

    The weight of the second system will be the weight of the first system.


ID is: 3659 Seed is: 5624

Proportional reasoning with Fg, m, and g

The relationship Fg=mg is a useful equation in mechanics. It is the mathematical statement that shows the relationship between weight, mass, and a planet's local gravitational acceleration.

Consider two objects with the same mass on different planets.

  1. What can we say about the relationship between the weight of each object and the local gravitational acceleration?

    Answer:

    The weight is the local gravitational acceleration.

  2. Consider the options below and choose the one that represents the relationship between weight and local gravitational acceleration symbolically:

    A Fgโˆ1g
    B Fg<g
    C Fg=g
    D Fgโˆg
    E Fg>g
    Answer:

    The correct option is .

  3. The gravitational acceleration of the second planet is 7 times smaller than the gravitational acceleration of the first planet. How does the weight of the second object compare to the weight of the first object?

    Answer:

    The weight of the second object will be the weight of the first object.



ID is: 3321 Seed is: 8975

Multiple choice: Proportional reasoning and the gravitational force

Two stars (H and J) are in deep space. H has mass m and J has mass m. The distance between their centres of mass is d. The gravitational force experienced by star J is F.

Consider a different system of two stars in which:

  • the mass of the first star is bigger than the mass of star H by a factor of 3,
  • the mass of the second star is bigger than the mass of star J by a factor of 2,
  • and the distance between the two stars is 12d.

What is the magnitude of the gravitational force experienced between these two stars in terms of the original force F?

A 32F
B 3F
C 12F
D 24F
Answer:

The correct option is:


ID is: 3321 Seed is: 6844

Multiple choice: Proportional reasoning and the gravitational force

Two planets (U and V) are in deep space. U has mass m and V has mass 4m. The distance between their centres of mass is d. The gravitational force experienced by planet V is F.

Consider a different system of two planets in which:

  • the mass of the first planet is the same as the mass of planet U,
  • the mass of the second planet is bigger than the mass of planet V by a factor of 4,
  • and the distance between the two planets is 13d.

What is the magnitude of the gravitational force experienced between these two planets in terms of the original force F?

A 169F
B 163F
C 43F
D 36F
Answer:

The correct option is:



ID is: 1476 Seed is: 2713

Effect of gravitational force on distance

A satellite circles around the Earth at a certain height above the surface of the Earth. At this height the gravitational force is a factor 16 less than at the surface of the Earth.

If the Earth's radius is RE, calculate the height of the satellite above the surface of the Earth in terms of the radius of the Earth.

INSTRUCTION: Write your answer as a multiple of RE.
Answer: Rorbit= RE
numeric

ID is: 1476 Seed is: 6264

Effect of gravitational force on distance

A satellite circles around the Earth at a certain height above the surface of the Earth. At this height the gravitational force is a factor 25 less than at the surface of the Earth.

If the Earth's radius is RE, calculate the height of the satellite above the surface of the Earth in terms of the radius of the Earth.

INSTRUCTION: Write your answer as a multiple of RE.
Answer: Rorbit= RE
numeric


ID is: 1540 Seed is: 741

Effect of mass on gravitational force

Two objects of mass 4x and 7x respectively exert a force F1 on each other when they are a distance D apart. What will the force be between two objects with masses 10x and 6x, also separated by the distance D, be?

INSTRUCTION: Write your answer as a fraction (or, where appropriate, as an integer).
Answer:

F2= F1

fraction

ID is: 1540 Seed is: 772

Effect of mass on gravitational force

Two objects of mass 3x and 9x respectively exert a force F1 on each other when they are a distance D apart. What will the force be between two objects with masses 7x and 8x, also separated by the distance D, be?

INSTRUCTION: Write your answer as a fraction (or, where appropriate, as an integer).
Answer:

F2= F1

fraction


ID is: 1543 Seed is: 5627

Comparing masses of different planets

The weight of a rock lying on surface of Earth is FE. The radius of Earth is RE. On planet Eta, the same rock has weight 9FE. If the radius of planet Eta is three times that of Earth, and the mass of Earth is ME, then what is the mass of Eta in terms of ME?

INSTRUCTION: Round your answer to the nearest integer.
Answer: Mฮท = ME
numeric

ID is: 1543 Seed is: 7233

Comparing masses of different planets

The weight of a rock lying on surface of Venus is FV. The radius of Venus is RV. On planet Eta, the same rock has weight 4FV. If the radius of planet Eta is half that of Venus, and the mass of Venus is MV, then what is the mass of Eta in terms of MV?

INSTRUCTION: Round your answer to the nearest integer.
Answer: Mฮท = MV
numeric


ID is: 3319 Seed is: 1474

Comparing gravitational forces

Two asteroids (K and L) are in deep space. K has mass m and L has mass m. The distance between their centres of mass is d. The gravitational force experienced by asteroid L is F.

Consider a different system of two asteroids in which:

  • the mass of the first asteroid is bigger than the mass of asteroid K by a factor of 2,
  • the mass of the second asteroid is bigger than the mass of asteroid L by a factor of 3,
  • and the distance between the two asteroids is 2d.

What is the magnitude of the gravitational force experienced between these two asteroids in terms of the original force F?

INSTRUCTION: Write your answer as a non-decimal fraction or as a whole number (whichever is more appropriate).
Answer:

Fnew= F

fraction

ID is: 3319 Seed is: 6102

Comparing gravitational forces

Two moons (U and V) are in deep space. U has mass m and V has mass 4m. The distance between their centres of mass is d. The gravitational force experienced by moon V is F.

Consider a different system of two moons in which:

  • the mass of the first moon is bigger than the mass of moon U by a factor of 3,
  • the mass of the second moon is bigger than the mass of moon V by a factor of 4,
  • and the distance between the two moons is d.

What is the magnitude of the gravitational force experienced between these two moons in terms of the original force F?

INSTRUCTION: Write your answer as a non-decimal fraction or as a whole number (whichever is more appropriate).
Answer:

Fnew= F

fraction


ID is: 1480 Seed is: 1787

Effect of distance on gravitational force

A satellite experiences a gravitational force F when at the surface of the Earth.

What will the gravitational force on the satellite be if it orbits at a height (above the surface of the Earth) equal to the diameter of the Earth?

INSTRUCTION: Write your answer as an exact fraction of F. Do not round off your answer.
Answer:

Forbit= F

numeric

ID is: 1480 Seed is: 8462

Effect of distance on gravitational force

A satellite experiences a gravitational force F when at the surface of the Earth.

What will the gravitational force on the satellite be if it orbits at a height (above the surface of the Earth) equal to three times the radius of the Earth?

INSTRUCTION: Write your answer as an exact fraction of F. Do not round off your answer.
Answer:

Forbit= F

numeric


ID is: 4015 Seed is: 3094

Multiple choice: Weight and gravity on other planets

Adapted from WCED Metro Central Sep 2017 Grade 12, P1, Q1.2 & DBE Nov 2016 Grade 11 P1, Q1.4
Physical constants ยท Physics formulas

Planet X has a third of the mass of the Earth and double the radius of the Earth. If the acceleration due to gravity on Earth is g, then the gravitational acceleration on Planet X will be ...

A 16g
B 43g
C 23g
D 112g
Answer:

ID is: 4015 Seed is: 6672

Multiple choice: Weight and gravity on other planets

Adapted from WCED Metro Central Sep 2017 Grade 12, P1, Q1.2 & DBE Nov 2016 Grade 11 P1, Q1.4
Physical constants ยท Physics formulas

Planet X has double the mass of the Earth and a third of the radius of the Earth. If the weight of an astronaut on Earth is W, then the weight of the astronaut on Planet X will be ...

A 18W
B 23W
C 29W
D 6W
Answer:

16. Chapter summary